The atypical organization of the luxI/R family genes in AHL-driven quorum-sensing circuits.

Abstract

Quorum sensing (QS) is an elaborate regulatory mechanism associated with virulence and bacterial adaptation to the changing environment. QS is widespread in Proteobacteria and acts primarily through N-acylhomoserine lactone (AHL) signals. At the core of the AHL-driven QS systems are the AHL synthase gene (luxI family) and its cognate transcriptional regulator gene (luxR family). Several QS systems display one or more genes intervening between the luxI and luxR, in which gene arrangements are notably different due to the relative position and the transcriptional orientation between the essential luxI/R and the genes of location correlation. These adjacent genes may exert a regulatory impact on the primary QS genes or contribute toward an extension of QS regulatory control. In this review, we describe the organization of AHL-driven QS genes based on previous research and specific genome databases and provide new insights into these atypical QS gene arrangements.