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- Title
The sil Locus in Streptococcus Anginosus Group: Interspecies Competition and a Hotspot of Genetic Diversity.
- Authors
Mendonca, Michelle L.; Szamosi, Jake C.; Lacroix, Anne-Marie; Fontes, Michelle E.; Bowdish, Dawn M.; Surette, Michael G.; Shinya Watanabe; Atsushi Tabata; Miki Kawada-Matsuo; Atsuo Sakurai
- Abstract
The Streptococcus Invasion Locus (Sil) was first described in Streptococcus pyogenes and Streptococcus pneumoniae, where it has been implicated in virulence. The twocomponent peptide signaling system consists of the SilA response regulator and SilB histidine kinase along with the SilCR signaling peptide and SilD/E export/processing proteins. The presence of an associated bacteriocin region suggests this system may play a role in competitive interactions with other microbes. Comparative analysis of 42 Streptococcus Anginosus/Milleri Group (SAG) genomes reveals this to be a hot spot for genomic variability. A cluster of bacteriocin/immunity genes is found adjacent to the sil system in most SAG isolates (typically 6-10 per strain). In addition, there were two distinct SilCR peptides identified in this group, denoted here as SilCRSAG-A and SilCRSAG-B, with corresponding alleles in silB. Our analysis of the 42 sil loci showed that SilCRSAG-A is only found in Streptococcus intermedius while all three species can carry SilCRSAG-B. In S. intermedius B196, a putative SilA operator is located upstream of bacteriocin gene clusters, implicating the sil system in regulation of microbe-microbe interactions at mucosal surfaces where the group resides. We demonstrate that S. intermedius B196 responds to its cognate SilCRSAG-A; and, less effectively, to SilCRSAG-B released by other Anginosus group members, to produce putative bacteriocins and inhibit the growth of a sensitive strain of S. constellatus.
- Subjects
STREPTOCOCCUS genetics; LOCUS (Genetics); BACTERIOCINS
- Publication
Frontiers in Microbiology, 2017, Vol 7, p1
- ISSN
1664-302X
- Publication type
Article
- DOI
10.3389/fmicb.2016.02156