Subject(s)
Biofilms/growth & development , Gene Expression Profiling/methods , Oligonucleotide Array Sequence Analysis/methods , Vibrio cholerae/genetics , Vibrio cholerae/physiology , DNA, Complementary/genetics , Genome, Bacterial , Humans , Open Reading Frames , Phenotype , Polymerase Chain Reaction , RNA, Bacterial/genetics , RNA, Bacterial/isolation & purification , Vibrio cholerae/classification , Vibrio cholerae/pathogenicityABSTRACT
The rugose colonial variant of Vibrio cholerae O1 El Tor produces an exopolysaccharide (EPS(ETr)) that enables the organism to form a biofilm and to resist oxidative stress and the bactericidal action of chlorine. Transposon mutagenesis of the rugose variant led to the identification of vpsR, which codes for a homologue of the NtrC subclass of response regulators. Targeted disruption of vpsR in the rugose colony genetic background yielded a nonreverting smooth-colony morphotype that produced no detectable EPS(ETr) and did not form an architecturally mature biofilm. Analysis of two genes, vpsA and vpsL, within the vps cluster of EPS(ETr) biosynthesis genes revealed that their expression is induced above basal levels in the rugose variant, compared to the smooth colonial variant, and requires vpsR. These results show that VpsR functions as a positive regulator of vpsA and vpsL and thus acts to positively regulate EPS(ETr) production and biofilm formation.
Subject(s)
Bacterial Proteins/genetics , Biofilms/growth & development , Polysaccharides, Bacterial/biosynthesis , Vibrio cholerae/genetics , Amino Acid Sequence , Bacterial Proteins/chemistry , Bacterial Proteins/physiology , Cloning, Molecular , DNA Transposable Elements , Gene Deletion , Gene Expression Regulation, Bacterial , Gene Targeting , Genes, Regulator , Molecular Sequence Data , Mutagenesis, Insertional , Phenotype , Polysaccharides, Bacterial/genetics , Sequence Analysis, DNA , Signal Transduction , Transcription, Genetic , Vibrio cholerae/classification , Vibrio cholerae/growth & development , Vibrio cholerae/metabolismABSTRACT
We have isolated, from the prokaryotic cyanobacterium Synechococcus sp. strain PCC 7942, a gene encoding a protein of 72 amino acids [designated high light inducible protein (HLIP)] with similarity to the extended family of eukaryotic chlorophyll a/b binding proteins (CABs). HLIP has a single membrane-spanning alpha-helix, whereas both the CABs and the related early light inducible proteins have three membrane-spanning helices. Hence, HLIP may represent an evolutionary progenitor of the eukaryotic members of the CAB extended family. We also show that the gene encoding HLIP is induced by high light and blue/UV-A radiation. The evolution, regulation, and potential function of HLIP are discussed.
