Mol Microbiol. 2014 Aug 6. doi: 10.1111/mmi.12745. [Epub ahead of print]
Pbp2x Localizes Separately from Pbp2b and Other Peptidoglycan Synthesis Proteins during Later Stages of Cell Division of Streptococcus pneumoniae D39.
Tsui HC1, Boersma MJ, Vella SA, Kocaoglu O, Kuru E, Peceny JK, Carlson EE, VanNeuwenhze MS, Brun YV, Shaw SL, Winkler ME.
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Abstract
The relative localization patterns of class B penicillin-binding proteins Pbp2x and Pbp2b were used as positional indicators of septal and peripheral (side-wall-like) peptidoglycan (PG) synthesis, respectively, in the midcell regions of Streptococcus pneumoniae cells at different stages of division. We confirm that Pbp2x and Pbp2b are essential in the strain D39 genetic background, which differs from that of laboratory strains. We show that Pbp2b, like Pbp2x and class A Pbp1a, follows a different localization pattern than FtsZ and remains at division septa after FtsZ reappears at the equators of daughter cells. Pulse-experiments with fluorescent D-amino acids (FDAAs) were performed in wild-type cells and in cells in which Pbp2x activity was preferentially inhibited by methicillin or Pbp2x amount was depleted. These experiments show that Pbp2x activity separates from that of other PBPs to the centers of constricting septa in mid-to-late divisional cells resolved by high-resolution 3D-SIM microscopy. Dual-protein and protein-fluorescent vancomycin 2D and 3D-SIM immunofluorescence microscopy (IFM) of cells at different division stages corroborate that Pbp2x separates to the centers of septa surrounded by an adjacent constricting ring containing Pbp2b, Pbp1a, and regulators, StkP and MreC. The separate localization of Pbp2x suggests distinctive roles in completing septal PG synthesis and remodeling.
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KEYWORDS:
MreC; Pbp1a; Penicillin-binding proteins (PBPs); StkP; class B PBPs; peptidoglycan biosynthesis
PMID: 25099088 [PubMed - as supplied by publisher]
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