Vaccination Drives Changes in Metabolic and Virulence Profiles of Streptococcus pneumoniae.

PLoS Pathog. 2015 Jul 16;11(7):e1005034. doi: 10.1371/journal.ppat.1005034. eCollection 2015.

Vaccination Drives Changes in Metabolic and Virulence Profiles of Streptococcus pneumoniae.

Watkins ER1, Penman BS1, Lourenço J1, Buckee CO2, Maiden MC1, Gupta S1.

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Abstract

The bacterial pathogen, Streptococcus pneumoniae (the pneumococcus), is a leading cause of life-threatening illness and death worldwide. Available conjugate vaccines target only a small subset (up to 13) of >90 known capsular serotypes of S. pneumoniae and, since their introduction, increases in non-vaccine serotypes have been recorded in several countries: a phenomenon termed Vaccine Induced Serotype Replacement (VISR). Here, using a combination of mathematical modelling and whole genome analysis, we show that targeting particular serotypes through vaccination can also cause their metabolic and virulence-associated components to transfer through recombination to non-vaccine serotypes: a phenomenon we term Vaccine-Induced Metabolic Shift (VIMS). Our results provide a novel explanation for changes observed in the population structure of the pneumococcus following vaccination, and have important implications for strain-targeted vaccination in a range of infectious disease systems.

PMID: 26181911 [PubMed - in process] PMCID: PMC4504489

Identification of PblB mediating galactose-specific adhesion in a successful Streptococcus pneumoniae clone.

Sci Rep. 2015 Jul 21;5:12265. doi: 10.1038/srep12265.

Identification of PblB mediating galactose-specific adhesion in a successful Streptococcus pneumoniae clone.

Hsieh YC1, Lin TL2, Lin CM1, Wang JT3.

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Abstract

The pneumococcal genome is variable and there are minimal data on the influence of the accessory genome on phenotype. Pneumococcal serotype 14 sequence type (ST) 46 had been the most prevalent clone causing pneumonia in children in Taiwan. A microarray was constructed using the genomic DNA of a clinical strain (NTUH-P15) of serotype 14 ST46. Using DNA hybridization, genomic variations in NTUH-P15 were compared to those of 3 control strains. Microarray analysis identified 7 genomic regions that had significant increases in hybridization signals in the NTUH-P15 strain compared to control strains. One of these regions encoded PblB, a phage-encoded virulence factor implicated (in Streptococcus mitis) in infective endocarditis. The isogenic pblB mutant decreased adherence to A549 human lung epithelial cell compared to wild-type NTUH-P15 strain (P = 0.01). Complementation with pblB restored the adherence. PblB is predicted to contain a galactose-binding domain-like region. Preincubation of NTUH-P15 with D-galactose resulted in decreases of adherence to A549 cell in a dose-dependent manner. Challenge of mice with NTUH-P15, isogenic pblB mutant and pblB complementation strains determined that PblB was required for bacterial persistence in the nasopharynx and lung. PblB, as an adhesin mediating the galactose-specific adhesion activity of pneumococci, promote pneumococcal clonal success.

PMID: 26193794 [PubMed - in process] PMCID: PMC4508584 

Chemical Synthesis Elucidates the Immunological Importance of a Pyruvate Modification in the Capsular Polysaccharide of Streptococcus pneumoniae Serotype 4.

Angew Chem Int Ed Engl. 2015 Jul 24. doi: 10.1002/anie.201504847. [Epub ahead of print]

Chemical Synthesis Elucidates the Immunological Importance of a Pyruvate Modification in the Capsular Polysaccharide of Streptococcus pneumoniae Serotype 4.

Pereira CL1,2, Geissner A3,4, Anish C3,4, Seeberger PH5,6.

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Abstract

Carbohydrate modifications are believed to strongly affect the immunogenicity of glycans. Capsular polysaccharides (CPS) from bacterial pathogens are frequently equipped with a pyruvate that can be placed across the 4,6-, 3,4-, or 2,3-positions. A trans-2,3-linked pyruvate is present on the CPS of the Gram-positive bacterium Streptococcus pneumoniae serotype 4 (ST4), a pathogen responsible for pneumococcal infections. To assess the immunological importance of this modification within the CPS repeating unit, the first total synthesis of the glycan was carried out. Glycan microarrays containing a series of synthetic antigens demonstrated how antibodies raised against natural ST4 CPS specifically recognize the pyruvate within the context of the tetrasaccharide repeating unit. The pyruvate modification is a key motif for designing minimal synthetic carbohydrate vaccines for ST4.

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

KEYWORDS:

Streptococcus pneumoniae; antigens; oligosaccharides; pyruvate acetal; synthetic vaccines

PMID: 26212109 [PubMed - as supplied by publisher]

Inclusion bodies and pH lowering: as an effect of gold nanoparticles in Streptococcus pneumoniae.

Metallomics. 2015 May 12. [Epub ahead of print]

Inclusion bodies and pH lowering: as an effect of gold nanoparticles in Streptococcus pneumoniae.

Ortiz-Benitez EA1, Carrillo-Morales M, Velázquez-Guadarrama N, Fandiño-Armas J, Olivares-Trejo JJ.

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Abstract

Streptococcus pneumoniae is a human pathogen whose principal virulence factor is its capsule. This structure allows the bacterium to evade the human immune system. Treatment of infections caused by this bacterium is based on antibiotics; however, the emergence of antibiotic-resistant strains makes this task increasingly difficult. Therefore, it is necessary to investigate new therapies, such as those based on gold nanoparticles, for which unfortunately the mechanisms involved have not yet been investigated. As far as we know, this study is the first that attempts to explain how gold nanoparticles destroy the bacterium Streptococcus pneumoniae. We found that the mean particle size was an important issue, and that the effect on the bacterium was dose-dependent. Cellular growth was inhibited by the presence of the nanoparticles, as was cell viability. The pH of the bacterial growth media was acidified, but interestingly the reactive species were not affected. A transmission electron microscopy analysis revealed the presence of inclusion bodies of gold nanoparticles within the bacterium. We present the first findings that attempt to explain how gold nanoparticles lyse Gram-positive bacteria.

PMID: 25966022 [PubMed - as supplied by publisher]

Formation of Streptococcus pneumoniae choline-binding protein-DNA complexes in vitro. Implications for biofilm development.

Environ Microbiol Rep. 2015 May 7. doi: 10.1111/1758-2229.12295. [Epub ahead of print]

Formation of Streptococcus pneumoniae choline-binding protein-DNA complexes in vitro. Implications for biofilm development.

Domenech M1, Ruiz S, Moscoso M, García E.

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Abstract

Extracellular DNA (eDNA) is an essential component of bacterial biofilm matrices, and is required in their formation and maintenance. eDNA binds to exopolysaccharides or extracellular proteins, affording biofilms greater structural integrity. Recently, we reported evidence of intercellular eDNA-LytC complexes in pneumococcal biofilms. The LytC lysozyme is a member of the choline-binding family of proteins (CBPs) located on the pneumococcal surface. The present work shows that other CBPs, i.e., LytA, LytB, Pce, PspC and CbpF, which also have a pI between 5 and 6, can bind DNA in vitro. This process requires the presence of divalent cations other than Mg2+ . This DNA binding capacity of CBPs appears to be independent of their enzymatic activity and, at least in the case of LytA, does not require the choline-binding domain characteristic of CBPs. Positively charged, surface-exposed, 25 amino acid-long peptides derived from the catalytic domain of LytB, were also found capable of DNA binding through electrostatic interactions. Confocal laser scanning microcopy revealed the existence of cell-associated LytB-eDNA complexes in Streptococcus pneumoniae biofilms. These and other findings suggest that these surface-located proteins of S. pneumoniae could play roles of varying importance in the colonization and/or invasion of human host where different environmental conditions exist.

This article is protected by copyright. All rights reserved.

PMID: 25950767 [PubMed - as supplied by publisher]

Long-term survival of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis as isolates and in nasopharyngeal specimens in frozen STGG storage medium.

J Microbiol Methods. 2015 Apr 30;114:38-39. doi: 10.1016/j.mimet.2015.04.012. [Epub ahead of print]

Long-term survival of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis as isolates and in nasopharyngeal specimens in frozen STGG storage medium.

Kaijalainen T1, Palmu A2.

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Abstract

We evaluated survival in WHO-recommended STGG storage medium of bacteria causing respiratory-tract infection. Streptococcus pneumoniae and Moraxella catarrhalis survived as single and mixed isolates stored at -70°C for 12.5years, but Haemophilus influenzae less than 4years. All the bacteria survived in the nasopharyngeal specimens at -70°C for 11years.

Copyright © 2015 Elsevier B.V. All rights reserved.

KEYWORDS:

Deep-freeze; Long-term survival; Respiratory-tract bacteria; STGG storage medium

PMID: 25937246 [PubMed - as supplied by publisher]

Streptococcus pneumoniae GAPDH Is Released by Cell Lysis and Interacts with Peptidoglycan.

PLoS One. 2015 Apr 30;10(4):e0125377. doi: 10.1371/journal.pone.0125377. eCollection 2015.

Streptococcus pneumoniae GAPDH Is Released by Cell Lysis and Interacts with Peptidoglycan.

Terrasse R1, Amoroso A2, Vernet T1, Di Guilmi AM1.

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Abstract

Release of conserved cytoplasmic proteins is widely spread among Gram-positive and Gram-negative bacteria. Because these proteins display additional functions when located at the bacterial surface, they have been qualified as moonlighting proteins. The GAPDH is a glycolytic enzyme which plays an important role in the virulence processes of pathogenic microorganisms like bacterial invasion and host immune system modulation. However, GAPDH, like other moonlighting proteins, cannot be secreted through active secretion systems since they do not contain an N-terminal predicted signal peptide. In this work, we investigated the mechanism of GAPDH export and surface retention in Streptococcus pneumoniae, a major human pathogen. We addressed the role of the major autolysin LytA in the delivery process of GAPDH to the cell surface. Pneumococcal lysis is abolished in the ΔlytA mutant strain or when 1% choline chloride is added in the culture media. We showed that these conditions induce a marked reduction in the amount of surface-associated GAPDH. These data suggest that the presence of GAPDH at the surface of pneumococcal cells depends on the LytA-mediated lysis of a fraction of the cell population. Moreover, we demonstrated that pneumococcal GAPDH binds to the bacterial cell wall independently of the presence of the teichoic acids component, supporting peptidoglycan as a ligand to surface GAPDH. Finally, we showed that peptidoglycan-associated GAPDH recruits C1q from human serum but does not activate the complement pathway.

PMID: 25927608 [PubMed - in process] PMCID: PMC4415926 

Carbon catabolite repression by seryl phosphorylated HPr is essential to Streptococcus pneumoniae in carbohydrate rich environments.

Mol Microbiol. 2015 Apr 21. doi: 10.1111/mmi.13033. [Epub ahead of print]

Carbon catabolite repression by seryl phosphorylated HPr is essential to Streptococcus pneumoniae in carbohydrate rich environments.

Fleming E1, Lazinski DW, Camilli A.

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Abstract

Carbon catabolite repression (CCR) is a regulatory phenomenon implemented by bacteria to hierarchically organize carbohydrate utilization in order to achieve maximal growth. CCR is likely of great importance to Streptococcus pneumoniae because the human host sites inhabited by this pathogen represent complex carbohydrate environments. In this species, inactivation of the prototypical Gram positive CCR master regulator, ccpA, attenuates virulence in mice but does not relieve CCR of most metabolic enzymes, suggesting CcpA-independent CCR mechanisms predominate. Here we show the activities of three transcriptional regulators constitute the majority of transcriptional CCR of galactose metabolism operons. We determined seryl-phosphorylated histidine phosphocarrier protein (HPr-Ser∼P)-mediated regulation is a major CCR mechanism and an essential activity in the pneumococcus, since an HPr point mutation abolishing HPrK/P-dependent phosphorylation was not tolerated nor was deletion of hprk/p. The HPr-Ser∼P phosphomimetic mutant HPr S46D had reduced PTS transport rates and limited induction of CCR-repressed genes. These results support a model of pneumococcal CCR in which HPr-Ser∼P directly affects the activity of CcpA while indirectly affecting the activity of pathway-specific transactional regulators. This report describes the first CcpA-independent CCR mechanism identified in the pneumococcus, and the first example of lethality from loss of HPr-Ser∼P-mediated CCR in any species.

This article is protected by copyright. All rights reserved.

KEYWORDS:

CcpA-independent carbon catabolite repression; Streptococcus pneumoniae; histidine phosphocarrier protein

PMID: 25898857

Copper intoxication inhibits aerobic nucleotide synthesis in Streptococcus pneumoniae.

Metallomics. 2015 Mar 2. [Epub ahead of print]

Copper intoxication inhibits aerobic nucleotide synthesis in Streptococcus pneumoniae.

Johnson MD1, Kehl-Fie TE, Rosch JW.

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Abstract

Copper is universally toxic in excess, a feature exploited by the human immune system to facilitate bacterial clearance. The mechanism of copper intoxication remains unknown for many bacterial species. Here, we demonstrate that copper toxicity in Streptococcus pneumoniae is independent from oxidative stress but, rather, is the result of copper inhibiting the aerobic dNTP biosynthetic pathway. Furthermore, we show that copper-intoxicated S. pneumoniae is rescued by manganese, which is an essential metal in the aerobic nucleotide synthesis pathway. These data provide insight into new targets to enhance copper-mediated toxicity during bacterial clearance.

PMID: 25730343 [PubMed - as supplied by publisher]

Dysregulation of transition metal ion homeostasis is the molecular basis for cadmium toxicity in Streptococcus pneumoniae.

Nat Commun. 2015 Mar 3;6:6418. doi: 10.1038/ncomms7418.

Dysregulation of transition metal ion homeostasis is the molecular basis for cadmium toxicity in Streptococcus pneumoniae.

Begg SL1, Eijkelkamp BA1, Luo Z2, Couñago RM2, Morey JR1, Maher MJ3, Ong CL4, McEwan AG4, Kobe B2, O'Mara ML5, Paton JC1, McDevitt CA1.

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Abstract

Cadmium is a transition metal ion that is highly toxic in biological systems. Although relatively rare in the Earth's crust, anthropogenic release of cadmium since industrialization has increased biogeochemical cycling and the abundance of the ion in the biosphere. Despite this, the molecular basis of its toxicity remains unclear. Here we combine metal-accumulation assays, high-resolution structural data and biochemical analyses to show that cadmium toxicity, in Streptococcus pneumoniae, occurs via perturbation of first row transition metal ion homeostasis. We show that cadmium uptake reduces the millimolar cellular accumulation of manganese and zinc, and thereby increases sensitivity to oxidative stress. Despite this, high cellular concentrations of cadmium (~17 mM) are tolerated, with negligible impact on growth or sensitivity to oxidative stress, when manganese and glutathione are abundant. Collectively, this work provides insight into the molecular basis of cadmium toxicity in prokaryotes, and the connection between cadmium accumulation and oxidative stress.

PMID: 25731976 [PubMed - in process]

Structural and Enzymatic Characterization of the Choline Kinase LicA from Streptococcus pneumoniae.

PLoS One. 2015 Mar 17;10(3):e0120467. doi: 10.1371/journal.pone.0120467. eCollection 2015.

Structural and Enzymatic Characterization of the Choline Kinase LicA from Streptococcus pneumoniae.

Wang L1, Jiang YL1, Zhang JR2, Zhou CZ1, Chen Y1.

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Abstract

LicA plays a key role in the cell-wall phosphorylcholine biosynthesis of Streptococcus pneumonia. Here we determined the crystal structures of apo-form LicA at 1.94 Å and two complex forms LicA-choline and LicA-AMP-MES, at 2.01 and 1.45 Å resolution, respectively. The overall structure adopts a canonical protein kinase-like fold, with the active site located in the crevice of the N- and C- terminal domains. The three structures present distinct poses of the active site, which undergoes an open-closed-open conformational change upon substrate binding and product release. The structure analyses combined with mutageneses and enzymatic assays enabled us to figure out the key residues for the choline kinase activity of LicA. In addition, structural comparison revealed the loop between helices α7 and α8 might modulate the substrate specificity and catalytic activity. These findings shed light on the structure and mechanism of the prokaryotic choline kinase LicA, and might direct the rational design of novel anti-pneumococcal drugs.

PMID: 25781969 [PubMed - in process] 

Following the equator: division site selection in Streptococcus pneumoniae.

Trends Microbiol. 2015 Feb 12. pii: S0966-842X(15)00028-1. doi: 10.1016/j.tim.2015.02.001. [Epub ahead of print]

Following the equator: division site selection in Streptococcus pneumoniae.

Bramkamp M1.

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Abstract

The mechanisms that spatially regulate cytokinesis are more diverse than initially thought. In two recent publications a positive regulator of FtsZ positioning has been identified in Streptococcus pneumoniae. MapZ (LocZ) connects the division machinery with cell wall elongation, providing a simple mechanism to ensure correct division site selection.

Copyright © 2015 Elsevier Ltd. All rights reserved.

KEYWORDS:

FtsZ; MapZ; Streptococcus pneumoniae; cell division; cell wall

PMID: 25684260 [PubMed - as supplied by publisher]

Uptake of extracellular DNA: Competence induced pili in natural transformation of Streptococcus pneumoniae.

Bioessays. 2015 Jan 15. doi: 10.1002/bies.201400125. [Epub ahead of print]

Uptake of extracellular DNA: Competence induced pili in natural transformation of Streptococcus pneumoniae.

Muschiol S1, Balaban M, Normark S, Henriques-Normark B.

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Abstract

Transport of DNA across bacterial membranes involves complex DNA uptake systems. In Gram-positive bacteria, the DNA uptake machinery shares fundamental similarities with type IV pili and type II secretion systems. Although dedicated pilus structures, such as type IV pili in Gram-negative bacteria, are necessary for efficient DNA uptake, the role of similar structures in Gram-positive bacteria is just beginning to emerge. Recently two essentially very different pilus structures composed of the same major pilin protein ComGC were proposed to be involved in transformation of the Gram-positive bacterium Streptococcus pneumoniae - one is a long, thin, type IV pilus-like fiber with DNA binding capacity and the other one is a pilus structure that was thicker, much shorter and not able to bind DNA. Here we discuss how competence induced pili, either by pilus retraction or by a transient pilus-related opening in the cell wall, may mediate DNA uptake in S. pneumoniae.

© 2015 The Authors. Bioessays published by WILEY Periodicals, Inc.

KEYWORDS:

Streptococcus pneumoniae; competence pilus; pneumococci; transformation

PMID: 25640084 [PubMed - as supplied by publisher]

Proteomic analysis of the copper resistance of Streptococcus pneumoniae.

Metallomics. 2015 Jan 22. [Epub ahead of print]

Proteomic analysis of the copper resistance of Streptococcus pneumoniae.

Guo Z1, Han J, Yang XY, Cao K, He K, Du G, Zeng G, Zhang L, Yu G, Sun Z, He QY, Sun X.

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Abstract

Streptococcus pneumoniae is a Gram-positive bacterial pathogen causing a variety of diseases, including otitis media, bacteraemia and meningitis. Although copper is an essential trace metal for bacterial growth, high intracellular levels of free-copper are toxic. Copper resistance has emerged as an important virulence determinant of microbial pathogens. In this study, we determined the minimum inhibition concentration of copper for the growth inhibition of S. pneumoniae. Two-dimensional-electrophoresis coupled with mass spectrometry was applied to identify proteins involved in copper resistance of S. pneumoniae. In total, forty-four proteins with more than 1.5-fold alteration in expression (p < 0.05) were identified. Quantitative reverse transcription PCR was used to confirm the proteomic results. Bioinformatics analysis showed that the differentially expressed proteins were mainly involved in the cell wall biosynthesis, protein biosynthesis, purine biosynthesis, pyrimidine biosynthesis, primary metabolic process, and the nitrogen compound metabolic process. Many up-regulated proteins in response to the copper treatment directly or indirectly participated in the cell wall biosynthesis, indicating that the cell wall is a critical determinant in copper resistance of S. pneumoniae.

PMID: 25608595 [PubMed - as supplied by publisher]

Structural determination of Streptococcus pneumoniae repeat units in serotype 41A and 41F capsular polysaccharides to probe gene functions in the corresponding capsular biosynthetic loci.

Carbohydr Res. 2014 Dec 5;400:26-32. doi: 10.1016/j.carres.2014.08.017. Epub 2014 Sep 16.

Structural determination of Streptococcus pneumoniae repeat units in serotype 41A and 41F capsular polysaccharides to probe gene functions in the corresponding capsular biosynthetic loci.

Petersen BO1, Skovsted IC2, Paulsen BS3, Redondo AR2, Meier S4.

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Abstract

We report the repeating unit structures of the native capsular polysaccharides of Streptococcus pneumoniae serotypes 41A and 41F. Structural determinations yielded six carbohydrate units in the doubly branched repeating unit to give the following structure for serotype 41A: The structure determinations were motivated (1) by an ambition to help close the remaining gaps in S. pneumoniae capsular polysaccharide structures, and (2) by the attempt to derive functional annotations of carbohydrate active enzymes in the biosynthesis of bacterial polysaccharides from the determined structures. An activity present in 41F but not 41A is identified as an acetyltransferase acting on the rhamnopyranosyl sidechain E. The genes encoding the formation of the six glycosidic bonds in serogroup 41 were determined from the capsular polysaccharide structures of serotype 41A, 41F, and genetically related serotypes, in conjunction with corresponding genomic information and computational homology searches. In combination with complementary information, NMR spectroscopy considerably simplifies the functional annotation of carbohydrate active enzymes in the biosynthesis of bacterial polysaccharides.

Copyright © 2014 Elsevier Ltd. All rights reserved.

KEYWORDS:

Biosynthetic loci; Capsular polysaccharide; NMR; Serotype 41A; Streptococcus pneumoniae

PMID: 25457607 [PubMed - in process]

MapZ marks the division sites and positions FtsZ rings in Streptococcus pneumoniae.

Nature. 2014 Nov 26. doi: 10.1038/nature13966. [Epub ahead of print]

MapZ marks the division sites and positions FtsZ rings in Streptococcus pneumoniae.

Fleurie A1, Lesterlin C2, Manuse S1, Zhao C1, Cluzel C3, Lavergne JP1, Franz-Wachtel M4, Macek B4, Combet C1, Kuru E5, VanNieuwenhze MS5, Brun YV5, Sherratt D2, Grangeasse C1.

Author information

Abstract

In every living organism, cell division requires accurate identification of the division site and placement of the division machinery. In bacteria, this process is traditionally considered to begin with the polymerization of the highly conserved tubulin-like protein FtsZ into a ring that locates precisely at mid-cell. Over the past decades, several systems have been reported to regulate the spatiotemporal assembly and placement of the FtsZ ring. However, the human pathogen Streptococcus pneumoniae, in common with many other organisms, is devoid of these canonical systems and the mechanisms of positioning the division machinery remain unknown. Here we characterize a novel factor that locates at the division site before FtsZ and guides septum positioning in pneumococcus. Mid-cell-anchored protein Z (MapZ) forms ring structures at the cell equator and moves apart as the cell elongates, therefore behaving as a permanent beacon of division sites. MapZ then positions the FtsZ ring through direct protein-protein interactions. MapZ-mediated control differs from previously described systems mostly on the basis of negative regulation of FtsZ assembly. Furthermore, MapZ is an endogenous target of the Ser/Thr kinase StkP, which was recently shown to have a central role in cytokinesis and morphogenesis of S. pneumoniae. We show that both phosphorylated and non-phosphorylated forms of MapZ are required for proper Z-ring formation and dynamics. Altogether, this work uncovers a new mechanism for bacterial cell division that is regulated by phosphorylation and illustrates that nature has evolved a diversity of cell division mechanisms adapted to the different bacterial clades.

PMID: 25470041 [PubMed - as supplied by publisher]

UlaR activates the expression of the ula operon in Streptococcus pneumoniae in the presence of ascorbic acid.

Microbiology. 2014 Oct 29. pii: mic.0.083899-0. doi: 10.1099/mic.0.083899-0. [Epub ahead of print]

UlaR activates the expression of the ula operon in Streptococcus pneumoniae in the presence of ascorbic acid.

Afzal M1, Shafeeq S2, Henriques-Normark B2, Kuipers OP3.

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Abstract

In this study, the regulatory mechanism of the ula (utilization of L-ascorbic acid) operon putatively responsible for transport and utilization of ascorbic acid in Streptococcus pneumoniae D39 strain is studied. β-galactosidase assay data demonstrate that the expression of the ula operon is increased in the presence of ascorbic acid, as compared to the effects of other sugar sources, including glucose. The ula operon consists of nine genes, including a BglG-family transcriptional regulator UlaR, and is transcribed as a single transcriptional unit. We demonstrate the role of the BglG-family transcriptional regulator UlaR as a transcriptional activator of the ula operon in the presence of ascorbic acid and show that activation of the ula operon genes by UlaR is CcpA-independent. Furthermore, we predict a 16-bp regulatory site (5'-AACAGTCCGCTGTGTA-3') for UlaR in the promoter region of ulaA. Deletion of the half- or full UlaR regulatory site in the PulaA confirmed that the UlaR regulatory site present in PulaA is functional.

Copyright © 2014, the Society for General Microbiology.

KEYWORDS:

Ascorbic acid; Pneumococcus; UlaR; carbon source; ula operon

PMID: 25355938 [PubMed - as supplied by publisher]

Topology of Streptococcus pneumoniae CpsC, a Polysaccharide co-polymerase and BY-kinase adaptor protein.

J Bacteriol. 2014 Oct 13. pii: JB.02106-14. [Epub ahead of print]

Topology of Streptococcus pneumoniae CpsC, a Polysaccharide co-polymerase and BY-kinase adaptor protein.

Whittall JJ1, Morona R1, Standish AJ2.

Author information

Abstract

In Gram-positive bacteria, tyrosine kinases are split into two proteins, the cytoplasmic tyrosine kinase and a transmembrane adaptor protein. In Streptococcus pneumoniae this transmembrane adaptor is CpsC, with the C-terminus of CpsC critical for interaction and subsequent tyrosine kinase activity of CpsD. Topology predictions suggest CpsC has two transmembrane domains, with the N and C-termini present in the cytoplasm. In order to investigate CpsC topology, we used a chromosomal HA-tagged Cps2C protein in D39. Incubation of both protoplasts and membranes with the CP-B resulted in complete degradation of HA-Cps2C in all cases, indicating that the C-terminus of Cps2C was likely extra-cytoplasmic, and hence the protein's topology was not as predicted. Similar results were seen with membranes from TIGR4, indicating Cps4C also showed similar topology. A chromosomally encoded fusion of HA-Cps2C and Cps2D was not degraded by CP-B, suggesting that the fusion fixed the C-terminus within the cytoplasm. However, capsule synthesis was unaltered by this fusion. Detection of the CpsC C-terminus by flow cytometry indicated that it was extra-cytoplasmic in approximately 30% of cells. Interestingly, a mutant in the protein tyrosine phosphatase CpsB had a significantly greater proportion of positive cells, although this affect was independent of its phosphatase activity. Our data indicate that CpsC possesses a varied topology, with the C-terminus flipping across the cytoplasmic membrane where it interacts with CpsD in order to regulate tyrosine kinase activity.

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

PMID: 25313397 [PubMed - as supplied by publisher]

Pronounced metabolic changes in adaptation to biofilm growth by Streptococcus pneumoniae.

PLoS One. 2014 Sep 4;9(9):e107015. doi: 10.1371/journal.pone.0107015. eCollection 2014.

Pronounced metabolic changes in adaptation to biofilm growth by Streptococcus pneumoniae.

Allan RN1, Skipp P2, Jefferies J3, Clarke SC4, Faust SN5, Hall-Stoodley L6, Webb J7.

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Abstract

Streptococcus pneumoniae accounts for a significant global burden of morbidity and mortality and biofilm development is increasingly recognised as important for colonization and infection. Analysis of protein expression patterns during biofilm development may therefore provide valuable insights to the understanding of pneumococcal persistence strategies and to improve vaccines. iTRAQ (isobaric tagging for relative and absolute quantification), a high-throughput gel-free proteomic approach which allows high resolution quantitative comparisons of protein profiles between multiple phenotypes, was used to interrogate planktonic and biofilm growth in a clinical serotype 14 strain. Comparative analyses of protein expression between log-phase planktonic and 1-day and 7-day biofilm cultures representing nascent and late phase biofilm growth were carried out. Overall, 244 proteins were identified, of which >80% were differentially expressed during biofilm development. Quantitatively and qualitatively, metabolic regulation appeared to play a central role in the adaptation from the planktonic to biofilm phenotype. Pneumococci adapted to biofilm growth by decreasing enzymes involved in the glycolytic pathway, as well as proteins involved in translation, transcription, and virulence. In contrast, proteins with a role in pyruvate, carbohydrate, and arginine metabolism were significantly increased during biofilm development. Downregulation of glycolytic and translational proteins suggests that pneumococcus adopts a covert phenotype whilst adapting to an adherent lifestyle, while utilization of alternative metabolic pathways highlights the resourcefulness of pneumococcus to facilitate survival in diverse environmental conditions. These metabolic proteins, conserved across both the planktonic and biofilm phenotypes, may also represent target candidates for future vaccine development and treatment strategies. Data are available via ProteomeXchange with identifier PXD001182.

PMID: 25188255 [PubMed - in process] PMCID: PMC4154835 

Chemical Interference with Iron Transport Systems to Suppress Bacterial Growth of Streptococcus pneumoniae.

PLoS One. 2014 Aug 29;9(8):e105953. doi: 10.1371/journal.pone.0105953. eCollection 2014.

Chemical Interference with Iron Transport Systems to Suppress Bacterial Growth of Streptococcus pneumoniae.

Yang XY1, Sun B2, Zhang L1, Li N1, Han J1, Zhang J1, Sun X1, He QY1.

Author information

Abstract

Iron is an essential nutrient for the growth of most bacteria. To obtain iron, bacteria have developed specific iron-transport systems located on the membrane surface to uptake iron and iron complexes such as ferrichrome. Interference with the iron-acquisition systems should be therefore an efficient strategy to suppress bacterial growth and infection. Based on the chemical similarity of iron and ruthenium, we used a Ru(II) complex R-825 to compete with ferrichrome for the ferrichrome-transport pathway in Streptococcus pneumoniae. R-825 inhibited the bacterial growth of S. pneumoniae and stimulated the expression of PiuA, the iron-binding protein in the ferrichrome-uptake system on the cell surface. R-825 treatment decreased the cellular content of iron, accompanying with the increase of Ru(II) level in the bacterium. When the piuA gene (SPD_0915) was deleted in the bacterium, the mutant strain became resistant to R-825 treatment, with decreased content of Ru(II). Addition of ferrichrome can rescue the bacterial growth that was suppressed by R-825. Fluorescence spectral quenching showed that R-825 can bind with PiuA in a similar pattern to the ferrichrome-PiuA interaction in vitro. These observations demonstrated that Ru(II) complex R-825 can compete with ferrichrome for the ferrichrome-transport system to enter S. pneumoniae, reduce the cellular iron supply, and thus suppress the bacterial growth. This finding suggests a novel antimicrobial approach by interfering with iron-uptake pathways, which is different from the mechanisms used by current antibiotics.

PMID: 25170896 [PubMed - in process] PMCID: PMC4149436