Transcriptional regulator involved in both the repression (at least 99 genes, such as mexR and algU) and in the activation (at least 203 genes, such as mvfR, rsaL, vqsR and rpoS) of regulatory or putative regulatory proteins which are implicated in quorum sensing, virulence and multidrug resistance. Mutation in vqsM resulted in loss of proteolytic and elastase activity, significantly decreased expression of lasI and rhlI, which are responsible for acyl homoserine lactone (acyl-HSL) biosynthesis, much reduced swimming and swarming capacity as well as decreased capacity of killing C.elegans.