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Transcriptional regulators of the GAD acid stress island are carried by effector protein‐encoding prophages and indirectly control type III secretion in enterohemorrhagic Escherichia coli O157:H7
Author(s) -
Tree Jai J.,
Roe Andrew J.,
Flockhart Allen,
McAteer Sean P.,
Xu Xuefang,
Shaw Darren,
Mahajan Arvind,
Beatson Scott A.,
Best Angus,
Lotz Sabrina,
Woodward Martin J.,
La Ragione Roberto,
Murphy Kenan C.,
Leong John M.,
Gally David L.
Publication year - 2011
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2011.07650.x
Subject(s) - biology , prophage , effector , escherichia coli , genetics , secretion , gene , microbiology and biotechnology , bacteriophage , biochemistry
Summary Type III secretion (T3S) plays a pivotal role in the colonization of ruminant hosts by Enterohemorrhagic Escherichia coli (EHEC). The T3S system translocates effector proteins into host cells to promote bacterial attachment and persistence. The repertoire and variation in prophage regions underpins differences in the pathogenesis and epidemiology of EHEC strains. In this study, we have used a collection of deletions in cryptic prophages and EHEC O157 O‐islands to screen for novel regulators of T3S. Using this approach we have identified a family of homologous AraC‐like regulators that indirectly repress T3S. These pro p hage‐encoded s ecretion r egulator genes ( psr ) are found exclusively on prophages and are associated with effector loci and the T3S activating Pch family of regulators. Transcriptional profiling, mutagenesis and DNA binding studies were used to show that these regulators usurp the conserved GAD acid stress resistance system to regulate T3S by increasing the expression of GadE (YhiE) and YhiF and that this regulation follows attachment to bovine epithelial cells. We further demonstrate that PsrA and effectors encoded within cryptic prophage CP933‐N are required for persistence in a ruminant model of colonization.