Expression and regulation of the Escherichia coli O157:H7 effector proteins NleH1 and NleH2

Schmidt, E.E., Holmes, A., Lindestam Arlehamn, C.S., Wang, D., Mitchell, T.J., Evans, T.J. and Roe, A.J. (2012) Expression and regulation of the Escherichia coli O157:H7 effector proteins NleH1 and NleH2. PLoS ONE, 7(3), e33408. (doi:10.1371/journal.pone.0033408) (PMID:22428045) (PMCID:PMC3299786)

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Abstract

E. coli O157 carries two genes encoding the effector proteins NleH1 and NleH2 which are 87% identical. Despite the similarity between the proteins, the promoter regions upstream of the genes encoding the effectors are more divergent suggesting that the actual expression of the genes may be differentially regulated. This was tested by creating reporter fusions and examining their expression in different genetic backgrounds, media and on contact with host cells. The function of the proteins was also tested following transfection into host cells.Expression of both NleH1 and NleH2 was enhanced when cultured under conditions that stimulated expression of the Type Three Secretion System (T3SS) and was influenced by the regulators Ler and GrlA. Maximal expression of NleH1 required 531 bp of the upstream untranslated region but NleH2 required only 113 bp. Interestingly, contact with host cells strongly repressed expression of both NleH1 and NleH2. Following transfection, both proteins produced only minor effects on NF-κB activation when assessed using a NF-κB luciferase reporter assay, a result that is consistent with the recent report demonstrating the dependence on RPS3 for NleH1 modulation of NF-κB.This study demonstrates the importance of considering gene regulation when studying bacterial effector proteins. Despite their sequence similarity, NleH1 and NleH2 are expressed differentially and may, therefore, be translocated at distinct times during an infection.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Roe, Professor Andrew and Evans, Professor Tom and Wang, Mr Dai and Mitchell, Professor Timothy
Authors: Schmidt, E.E., Holmes, A., Lindestam Arlehamn, C.S., Wang, D., Mitchell, T.J., Evans, T.J., and Roe, A.J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:PLoS ONE
Publisher:Public Library of Science
ISSN:1932-6203
Published Online:12 March 2012
Copyright Holders:Copyright © 2012 The Authors
First Published:First published in PLoS One 7(32):e33408
Publisher Policy:Reproduced under a Creative Commons Licence

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
491441A biochemical and molecular analysis of the YhaO membrane protein in Escherichia coli O157:H7Andrew RoeBiotechnology and Biological Sciences Research Council (BBSRC)BB/G011389/1III - BACTERIOLOGY