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The expression of Longus type 4 pilus of enterotoxigenic Escherichia coli is regulated by LngR and LngS and by H‐NS, CpxR and CRP global regulators
Author(s) -
De la Cruz Miguel A.,
RuizTagle Alejandro,
Ares Miguel A.,
Pacheco Sabino,
Yáñez Jorge A.,
Cedillo Lilia,
Torres Javier,
Girón Jorge A.
Publication year - 2017
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.13644
Subject(s) - biology , pilus , enterotoxigenic escherichia coli , microbiology and biotechnology , escherichia coli , fimbriae proteins , genetics , gene , enterotoxin
Summary Enterotoxigenic Escherichia coli produces a long type 4 pilus called Longus. The regulatory elements and the environmental signals controlling the expression of Longus‐encoding genes are unknown. We identified two genes lngR and lngS in the Longus operon, whose predicted products share homology with transcriptional regulators. Isogenic lngR and lngS mutants were considerably affected in transcription of lngA pilin gene. The expression of lngA, lngR and lngS genes was optimally expressed at 37°C at pH 7.5. The presence of glucose and sodium chloride had a positive effect on Longus expression. The presence of divalent ions, particularly calcium, appears to be an important stimulus for Longus production. In addition, we studied H‐NS, CpxR and CRP global regulators, on Longus expression. The response regulator CpxR appears to function as a positive regulator of lng genes as the cpxR mutant showed reduced levels of lngRSA expression. In contrast, H‐NS and CRP function as negative regulators since expression of lngA was up‐regulated in isogenic hns and crp mutants. H‐NS and CRP were required for salt‐ and glucose‐mediated regulation of Longus. Our data suggest the existence of a complex regulatory network controlling Longus expression, involving both local and global regulators in response to different environmental signals.