An agr -Like Two-Component Regulatory System in Lactobacillus plantarum Is Involved in Production of a Novel Cyclic Peptide and Regulation of Adherence

Abstract

We have analyzed a locus on the annotated Lactobacillus plantarum WCFS1 genome that showed homology to the staphylococcal agr quorum-sensing system and designated it lam for Lactobacillus agr-like module. Production of the lamBDCA transcript was shown to be growth phase dependent. Analysis of a response regulator-defective mutant (⌬lamA) in an adherence assay showed that lam regulates adherence of L. plantarum to a glass surface. Global transcription analysis of the wild-type and ⌬lamA strains in early, mid-, and late log phase of growth was performed using a clone-based microarray. Remarkably, only a small set of genes showed significant differences in transcription profiles between the wild-type and lamA mutant strains. The microarray analysis confirmed that lamBDCA is autoregulatory and showed that lamA is involved in regulation of expression of genes encoding surface polysaccharides, cell membrane proteins, and sugar utilization proteins. The lamBD genes encoding the putative autoinducing peptide precursor (LamD) and its processing protein (LamB) were overexpressed using the nisin-controlled expression system, and culture supernatants were analyzed by liquid chromatography/mass spectrometry (LC/MS) to identify overproduced LamD-derived peptides. In this way, a cyclic thiolactone pentapeptide that possesses a ring structure similar to those of autoinducing peptides of the staphylococcal agr system was identified. The peptide was designated LamD558, and its sequence (CVGIW) matched the annotated precursor peptide sequence. Time course analysis of wild-type culture supernatants by LC/MS indicated that LamD558 production was increased markedly from mid-log to late log growth phase. This is the first example of an agr-like system in nonpathogenic bacteria that encodes a cyclic thiolactone autoinducing peptide and is involved in regulation of adherence.Regulation of physiological changes in bacterial populations in many cases has been shown to be dependent on specific cell densities and growth phases. This phenomenon of cell densitydependent gene expression has been termed quorum sensing and was initially found to regulate bioluminescence in Vibrio fischeri (15). Since then, a large variety of quorum-sensing systems has been discovered in both gram-negative and grampositive bacteria (29). Well-studied examples of quorum sensing-regulated features in gram-positive bacteria include genetic competence in Bacillus subtilis (55) and Streptococcus pneumoniae (8), virulence and biofilm formation in Staphylococcus aureus (39, 65) and Enterococcus faecalis (16,44), and the production of antimicrobial peptides, including bacteriocins and lantibiotics, in various lactic acid bacteria (26,38). To regulate these quorum-sensing systems, bacteria produce extracellular signaling molecules that are responsible for cell-tocell communication. While many gram-negative bacteria communicate via N-acyl-homoserine lactones, peptides are the most common and well-studied signaling molecules in grampositive bacteria; here these peptides are...

Multireplicon genome architecture of Lactobacillus salivarius

“…Cluster 2 (LSL 1547-LSL 1574) has lower GC content (29%) compared with the rest of the genome and comprises 21 EPS-related genes, interrupted by 7 genes of unknown or unrelated function; 14 of the genes in this cluster show significant homology to genes in the major EPS cluster of L. plantarum, but there is no extended synteny. This region of the L. plantarum genome also shows aberrant base composition and has recently been subdivided into three clusters, the second of which is up-regulated in a quorum-sensing mutant (35). L. salivarius EPS cluster 2 includes genes for a LytR-type transcriptional regulator, a flippase, and seven glycosyltransferases, including a priming glucose phosphotransferase (EpsE homolog; LSL 1550), and, thus, represents a more complete unit than Cluster 1, relative to characterized EPS operons.…”

Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

“…RNAIII is an intracellular effector that targets the production of virulence factors (Tegmark et al, 1998). Other known agr-like systems are ComDE of streptococci and FsrCA of Enterococcus faecalis, both involved in virulence (Lyon & Novick, 2004), and LamCA of Lactobacillus plantarum, which mediates the production of surface proteins and cell adherence (Sturme et al, 2005). Like many agr-like modules, TCS 68 of the B. cereus group might function as a quorum-sensing system, regulating the production of virulence factors and mediating host-microbe interactions.…”

Nonribosomal cyclic peptides: specific markers of fungal infections

“…Thiolactone autoinducing cyclic pentapeptide (cyclic AIP) is involved in Lactobacillus plantarum regulation of adherence and is similar in structure to those of peptides of the staphylococcal agr quorum-sensing system. 175 Structures of AIPs from Staphylococcus aureus and S. intermedius were detected by hypothesis-driven multistage mass spectrometry. 176 …”