Tn5253 family integrative and conjugative elements carrying mef(I) and catQ determinants in Streptococcus pneumoniae and Streptococcus pyogenes.

Antimicrob Agents Chemother. 2014 Jul 28. pii: AAC.03638-14. [Epub ahead of print]

Tn5253 family integrative and conjugative elements carrying mef(I) and catQ determinants in Streptococcus pneumoniae and Streptococcus pyogenes.

Mingoia M1, Morici E1, Morroni G1, Giovanetti E2, Del Grosso M3, Pantosti A3, Varaldo PE4.

Author information

Abstract

The linkage between the macrolide efflux gene mef(I) and the chloramphenicol inactivation gene catQ was first described in Streptococcus pneumoniae (strain Spn529), where the two genes are located in a module designated IQ element. Subsequently, two different, defective IQ elements were detected in Streptococcus pyogenes (strains Spy029 and Spy005). The genetic elements carrying the three IQ elements were characterized and all were found to be Tn5253 family integrative and conjugative elements (ICEs). The ICE from S. pneumoniae (ICESpn529IQ) was sequenced, whereas those from S. pyogenes (ICESpy029IQ and ICESpy005IQ, the first Tn5253-like ICEs reported in this species) were characterized by PCR mapping, partial sequencing and restriction analysis. ICESpn529IQ and ICESpy029IQ were found to share the intSp 23FST81 integrase gene and an identical Tn916 fragment, whereas ICESpy005IQ had int5252 and lacked Tn916. All three ICEs lacked the linearized pC194 plasmid that is usually associated to Tn5253-like ICEs, and all displayed a single copy of a toxin-antitoxin operon that is typically contained in the direct repeats flanking the excisable pC194 region when the latter is present. Two different insertion sites of the IQ elements were detected, one in ICESpn529IQ and ICESpy029IQ and another in ICESpy005IQ. The chromosomal integration of the three ICEs was site-specific, depending on the integrase (intSp 23FST81 or int5252). Only ICESpy005IQ was excised in circular form and transferred by conjugation. By transformation, mef(I) and catQ were cotransferred at high frequency from S. pyogenes Spy005, and at very low frequencies from S. pneumoniae Spn529 and S. pyogenes Spy029.

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

PMID: 25070090 [PubMed - as supplied by publisher]