title: Characterization of LuxI and LuxR Protein Homologs of N-Acylhomoserine Lactone-Dependent Quorum Sensing System in Pseudoalteromonas sp. 520P1.
abstract: Pseudoalteromonas sp. 520P1 (hereafter referred to as strain 520P1) produces N-acylhomoserine lactones (AHLs), which serve as signaling molecules in Gram-negative bacterial quorum sensing. In a previous genomic analysis of the 5.25-Mb genome of strain 520P1, we detected the presence of at least one homolog of the AHL synthase gene (luxI) and five homologs of the transcriptional regulator protein gene (luxR). The LuxI homolog of strain 520P1 (PalI) contained the conserved amino acid motifs shared by all the LuxI family proteins of the different species examined here. The palI gene expressed in Escherichia coli produced two types of AHLs. In the thin-layer chromatography analysis, these AHLs showed identical mobility to the AHLs produced by strain 520P1. The five LuxR homologs of strain 520P1 (PalR1-PalR5) shared only 17-34% amino acid sequence identity, although higher identities were observed in the C-terminal DNA-binding domain. Among the five PalRs, only PalR5 displayed close homology with LuxR family proteins from other Pseudoalteromonas strains. Notably, the palR3 and palI genes were located close together and only 1021 bases apart in the genome. No cognate luxI homolog associated with the four other palR genes was detected. These characteristics of PalI and the PalRs suggest that AHL autoinducers generated by the PalI enzyme might regulate cellular metabolism in cooperation with five transcriptional regulator PalRs, each of which is presumed to play a distinctive role in bacterial signaling.
authors.affiliation: School of Environmental Science and Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami, Kochi, 782-8502, Japan.
authors.forename: Hoang Tran
authors.initials: HT
authors.lastname: Dang
authors.affiliation: School of Environmental Science and Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami, Kochi, 782-8502, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Komatsu
authors.affiliation: School of Environmental Science and Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami, Kochi, 782-8502, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Masuda
authors.affiliation: School of Environmental Science and Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami, Kochi, 782-8502, Japan. enomoto.keiichi@kochi-tech.ac.jp.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Enomoto
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D008025:Ligases / Q000235:genetics*; D010802:Phylogeny; D031161:Pseudoalteromonas / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D053038:Quorum Sensing / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; C085427:LuxI protein, Bacteria; D011994:Recombinant Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C064778:LuxR autoinducer binding proteins; D008025:Ligases; C449816:N-acylhomoserine lactone synthase
keywords: LuxI/LuxR homologs; N-Acylhomoserine lactone; Pseudoalteromonas; Quorum sensing