Two homologous agr-like quorum-sensing systems cooperatively control adherence, cell morphology, and cell viability properties in Lactobacillus plantarum WCFS1

A two-component regulatory system of Lactobacillus plantarum, encoded by genes designated lamK and lamR (hpk10 and rrp10), was studied. The lamK and lamR genes encode proteins which are highly homologous to the quorum-sensing histidine kinase LamC and the response regulator LamA, respectively. Transcription analysis of the lamKR operon and the lamBDCA operon and liquid chromatography-mass spectrometry analysis of production of the LamD558 autoinducing peptide were performed for ΔlamA, ΔlamR, ΔlamA ΔlamR deletion mutants and a wild-type strain. The results suggested that lamA and lamR are cooperating genes. In addition, typical phenotypes of the ΔlamA mutant, such as reduced adherence to glass surfaces and filamentous cell morphology, were enhanced in the ΔlamA ΔlamR mutant. Microarray analysis suggested that the same cell wall polysaccharide synthesis genes, stress response-related genes, and cell wall protein-encoding genes were affected in the ΔlamA and ΔlamA ΔlamR mutants. However, the regulation ratio was more significant for the ΔlamA ΔlamR mutant, indicating the cooperative effect of LamA and LamR.