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| The EMBO Journal
(2000) 19, 1450–1457, doi:10.1093/emboj/19.7.1450 |
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| Regulatory cross-talk between adhesin operons in Escherichia coli: inhibition of type 1 fimbriae expression by the PapB protein |
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| Yan Xia1, David Gally2, Kristina Forsman-Semb1, 3 and Bernt Eric Uhlin1 |
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1 Department of Microbiology, Umeå University, S–90187 Umeå, Sweden 2 Zoonotic and Animal Pathogens Research Laboratories, Department of Veterinary Pathology, Medical Microbiology, Teviot Place, The University of Edinburgh, Edinburgh EH8 9AG, UK 3 Present address: AstraZeneca, Molecular Biology, S-43183 Mölndal, Sweden To whom correspondence should be addressed Bernt Eric Uhlin, bernt.eric.uhlin@micro.umu.se Received 26 November 1999; Revised 17 February 2000; Accepted 17 February 2000. |
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| Abstract |
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| Pathogenic Escherichia coli often carry determinants for several different adhesins. We show a direct communication between two adhesin gene clusters in uropathogenic E.coli: type 1 fimbriae (fim) and pyelonephritis-associated pili (pap). A regulator of pap, PapB, is a key factor in this cross-talk. FimB recombinase turns on type 1 fimbrial expression, and PapB inhibited phase transition by FimB in both off-to-on and on-to-off directions. On-to-off switching requiring FimE was increased by PapB. By analysis of FimB– and FimE–LacZ translational fusions it was concluded that the increase in on-to-off transition rates was via an increase in FimE expression. Inhibition of FimB-promoted switching was via a different mechanism: PapB inhibited FimB-promoted in vitro recombination, indicating that FimB activity was blocked at the fim switch. In vitro analyses showed that PapB bound to several DNA regions of the type 1 fimbrial operon, including the fim switch region. These data show that Pap expression turns off type 1 fimbriae expression in the same cell. Such cross-talk between adhesin gene clusters may bring about appropriate expression at the single cell level. |
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| Keywords: adhesion, cross-talk, fimbriae, phase switch, regulation |
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