Stress-related Pseudomonas genes involved in production of bacteriocin LlpA

Pseudomonas sp. BW11M1 produces a novel type of bacteriocin that inhibits the growth of Pseudomonas putida GR12-2R3 and some phytopathogenic fluorescent Pseudomonas. A collection of mutants was screened for altered bacteriocin production phenotypes. Strongly reduced bacteriocin production was found to be caused by inactivation of the recA gene or the spoT gene. Conversely, in a recJ mutant, the bacteriocin was constitutively overproduced. The same phenotype was observed for a mutant hit in a gene of unknown function. The predicted gene product belongs to a distinct subgroup of prokaryotic helicase-like proteins within the SWI/SNF family of regulatory proteins. One mutant that also exhibited a bacteriocin overproducer phenotype was deficient in the production of the peptidoglycan-associated lipoprotein OprL. This study shows that various environmental stress response pathways are involved in controlling expression of the Pseudomonas sp. BW11M1 bacteriocin.