title: Effect of growth conditions on poly-N-acetylglucosamine expression and biofilm formation in Escherichia coli.
abstract: Escherichia coli contains a four-gene operon, pgaABCD, which encodes the proteins necessary for the synthesis of polymeric N-acetylglucosamine, or PGA. Poly-N-acetyl-glucosamine was first described in Staphylococcus aureus and Staphylococcus epidermidis and was found to have important roles in biofilm formation and immune evasion. PGA also plays a role in biofilm formation in E. coli, but its role in immune evasion has not been thoroughly studied. We previously reported that E. coli PGA cross-reacts with an opsonic-antibody raised against S. aureus PNAG and this is the basis for an ongoing investigation regarding the development of a vaccine against both pathogens. In this paper we investigated pga expression in wild type and csrA or nhaR deletion mutant strains during different growth phases and temperatures, and in response to chemical stimuli using a pga promoter-reporter fusion construct, real-time reverse transcriptase-PCR, immunoblotting, and biofilm assays. Expression of pga and polysaccharide synthesis were induced by glucose, NaCl, and ethanol, but only glucose augmented biofilm formation. The regulatory factor NhaR was required for NaCl-induced pga expression, whereas the effects of glucose and ethanol were independent of CsrA and NhaR.
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: Nuno
authors.initials: N
authors.lastname: Cerca
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Jefferson
mesh_terms: D000117:Acetylglucosamine / Q000096:biosynthesis*; D018441:Biofilms / Q000254:growth & development*; D003470:Culture Media; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics; D000431:Ethanol; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D017930:Genes, Reporter; D005947:Glucose; D015151:Immunoblotting; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic; D016601:RNA-Binding Proteins / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride; D014157:Transcription Factors / Q000235:genetics
chemical_list: C093587:CsrA protein, E coli; D003470:Culture Media; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D011135:Polysaccharides, Bacterial; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C074687:nhaR protein, E coli; D000431:Ethanol; D012965:Sodium Chloride; D005947:Glucose; D000117:Acetylglucosamine