Expression of the O antigen gene cluster is regulated by RfaH through the JUMPstart sequence.
O antigen genes are clustered, with a JUMPstart sequence located upstream. JUMPstart is a 39-bp sequence, present upstream of many polysaccharide gene clusters and also upstream of haemolysin and F factor gene clusters. RfaH is known to regulate the expression of E. coli group II capsule, haemolysin, F factor and the outer core of lipopolysaccharide all of which have the JUMPstart sequence, and has been shown to function as a transcriptional antiterminator in some cases. Using lacZ fusions to genes in the O antigen gene cluster of Salmonella enterica serovar Typhimurium, we found that RfaH also regulates the expression of O antigen. We showed that RfaH enhances expression of the 18-kb O antigen gene cluster, with promoter-distal genes affected more dramatically. We also showed that the JUMPstart sequence was required for RfaH function.
Department of Microbiology, University of Sydney, Australia.
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Jensen
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Hallman
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Reeves
D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D005809:Genes, Regulator / Q000235:genetics*; D016254:Mutagenesis, Insertional; D019081:O Antigens; D010445:Peptide Elongation Factors / Q000235:genetics*; D019779:Salmonella enterica / Q000235:genetics / Q000276:immunology; D015534:Trans-Activators / Q000235:genetics*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D019081:O Antigens; D010445:Peptide Elongation Factors; C106401:RfaH protein, E coli; D015534:Trans-Activators