A broadly distributed new class of quorum sensing signals mediate bacterial intercellular signaling

Abstract

Abstract The gram-positive bacteria use quorum sensing secreted peptides to communicate and control critical bacterial phenotypes. All the bacterial peptides are produced in a longer inactive form that is secreted and processed into shorter active peptides. Recently, we discovered a new class of bacterial peptide in human pathogen Streptococcus pyogenes, a leaderless communication peptide (LCP), that is encoded as an 8 amino acid long active peptide without secretion signal sequence and processing sites. Nevertheless, LCP mediates intercellular communication and controls bacterial virulence. However, except for LCP from S. pyogenes, the occurrence of this unique class of intercellular signals in bacterial genomes and their contribution to bacterial biology remain unknown. Here, we report the widespread presence of LCPs among firmicutes encompassing broad taxonomic diversity and displaying diverse peptide communication codes. We further show that the newly identified LCPs act as bacterial intercellular signals and carry out gene regulation. Our results suggest that LCPs are more widespread than indicated by our study, and their characterization may uncover new signaling mechanisms and roles in coordinating diverse bacterial traits.