title: Antirepression function in Escherichia coli for the cAMP-cAMP receptor protein transcriptional activator.
abstract: The cAMP receptor protein (CRP) complex (cAMP-CRP) is a global regulator of gene expression. It influences transcription from a number of promoters in Escherichia coli, including two divergently oriented promoters in the pap pili-adhesin gene system. To further define the role of cAMP-CRP in pap regulation we monitored protein-DNA interactions in vitro and levels of pap transcription in vivo in wild-type and mutant pap-containing clones. The results showed that activation was mediated by a single cAMP-CRP-binding site centered at nucleotide positions -215.5 and -115.5 relative to the transcriptional start points. A target for the pap-specific regulatory protein PapB was localized adjacent to the cAMP-CRP-binding site. The long-range effects exerted from the protein-binding sites were consistent with the idea that cAMP-CRP caused a change in the local DNA conformation and that a nucleoprotein complex (involving cAMP-CRP and PapB) was formed in the region between the pap promoters. Moreover, transcription became independent of activation of cAMP-CRP and the PapB protein in a mutant lacking the nucleoid-associated protein H-NS. Our findings suggest that the cAMP-CRP complex mediates its positive regulatory function by alleviating transcriptional silencing and, as such, plays a role as antirepressor.
authors.affiliation: Department of Microbiology, University of Umeå, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Forsman
authors.forename: B
authors.initials: B
authors.lastname: Sondén
authors.forename: M
authors.initials: M
authors.lastname: Göransson
authors.forename: B E
authors.initials: BE
authors.lastname: Uhlin
mesh_terms: D018830:Adhesins, Escherichia coli; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D001426:Bacterial Proteins; D001483:Base Sequence; D000242:Cyclic AMP / Q000502:physiology*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D011953:Receptors, Cyclic AMP / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D018830:Adhesins, Escherichia coli; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; D009838:Oligodeoxyribonucleotides; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011953:Receptors, Cyclic AMP; D012097:Repressor Proteins; D014157:Transcription Factors; D000242:Cyclic AMP