Anagr-Like Two-Component Regulatory System inLactobacillus plantarumIs Involved in Production of a Novel Cyclic Peptide and Regulation of Adherence

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Abstract
We have analyzed a locus on the annotatedLactobacillus plantarumWCFS1 genome that showed homology to the staphylococcalagrquorum-sensing system and designated itlamforLactobacillus agr-like module. Production of thelamBDCAtranscript was shown to be growth phase dependent. Analysis of a response regulator-defective mutant (ΔlamA) in an adherence assay showed thatlamregulates adherence ofL. plantarumto a glass surface. Global transcription analysis of the wild-type and ΔlamAstrains 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 andlamAmutant strains. The microarray analysis confirmed thatlamBDCAis autoregulatory and showed thatlamAis involved in regulation of expression of genes encoding surface polysaccharides, cell membrane proteins, and sugar utilization proteins. ThelamBDgenes 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 staphylococcalagrsystem 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 anagr-like system in nonpathogenic bacteria that encodes a cyclic thiolactone autoinducing peptide and is involved in regulation of adherence.