Quorum-Sensing Regulon of Vibriofischeri: Novel Components of the Autoinducer/LuxR Regulatory Circuit

摘要

In this study five proteins regulated by quorum sensing are described from the marine bacterium Vibrio fischeri. Each protein is positively regulated by 30C6-HSL and LuxR and negatively regulated at low population density by C8- HSL. Probable LuxR/autoinducer binding sites are found in the promoter regions of the genes encoding each of the proteins. QsrP and RibB are encoded monocistronically, whereas AcfA and QsrV appear to be encoded by a two-gene operon. In competition assays with the parent strain, qsrP and acfA insertion mutants displayed altered colonization phenotypes with the squid symbiotic host. RibB is believed to be an enzyme that catalyzes an initial step of riboflavin synthesis and AcfA is believed to be a pilus subunit protein. The functions of QsrP and QsrV are unknown at this time. Oriented divergently from acfA are open reading frames that code for two putative members of the LysR family of transcriptional regulators. The shared promoter region suggests that transcription of acfA and qsrv may be regulated by one or both of these divergently transcribed proteins. This work defines a quorum-sensing regulon in V. fischeri. A model describing its regulation is presented.