title: A GntR-type transcriptional repressor controls sialic acid utilization in Bifidobacterium breve UCC2003.
abstract: Bifidobacterium breve strains are numerically prevalent among the gut microbiota of healthy, breast-fed infants. The metabolism of sialic acid, a ubiquitous monosaccharide in the infant and adult gut, by B. breve UCC2003 is dependent on a large gene cluster, designated the nan/nag cluster. This study describes the transcriptional regulation of the nan/nag cluster and thus sialic acid metabolism in B. breve UCC2003. Insertion mutagenesis and transcriptome analysis revealed that the nan/nag cluster is regulated by a GntR family transcriptional repressor, designated NanR. Crude cell extract of Escherichia coli EC101 in which the nanR gene had been cloned and overexpressed was shown to bind to two promoter regions within this cluster, each of which containing an imperfect inverted repeat that is believed to act as the NanR operator sequence. Formation of the DNA-NanR complex is prevented in the presence of sialic acid, which we had previously shown to induce transcription of this gene cluster.
authors: School of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Western Road, Cork, Ireland.
authors: Muireann
authors: M
authors: Egan
authors: School of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Western Road, Cork, Ireland.
authors: Mary
authors: M
authors: O'Connell Motherway
authors: School of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Western Road, Cork, Ireland d.vansinderen@ucc.ie.
authors: Douwe
authors: D
authors: van Sinderen
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001644:Bifidobacterium / Q000235:genetics* / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D009875:Operator Regions, Genetic; D011401:Promoter Regions, Genetic; D050436:Regulatory Elements, Transcriptional; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017421:Sequence Analysis
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012097:Repressor Proteins; D019158:N-Acetylneuraminic Acid
keywords: bifidobacteria; human milk oligosaccharides; mucin; neuraminic acid; transcriptional repression