Intracellular D-serine accumulation promotes genetic diversity via modulated induction of RecA in enterohemorrhagic Escherichia coli

Connolly, J. P.R. and Roe, A. J. (2016) Intracellular D-serine accumulation promotes genetic diversity via modulated induction of RecA in enterohemorrhagic Escherichia coli. Journal of Bacteriology, 198(24), pp. 3318-3328. (doi: 10.1128/JB.00548-16) (PMID:27698085) (PMCID:PMC5116935)

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Abstract

We recently discovered that exposure of enterohemorrhagic Escherichia coli (EHEC) to D-serine resulted in accumulation of this unusual amino acid, induction of the SOS regulon, and downregulation of the type III secretion system that is essential for efficient colonization of the host. Here, we have investigated the physiological relevance of this elevated SOS response, which is of particular interest given the presence of Stx toxin-carrying lysogenic prophages on the EHEC chromosome that are activated during the SOS response. We found that RecA elevation in response to D-serine, while being significant, was heterogeneous and not capable of activating stx expression or stx phage transduction to a nonlysogenic recipient. This “SOS-like response” was, however, capable of increasing the mutation frequency associated with low-level RecA activity, thus promoting genetic diversity. Furthermore, this response was entirely dependent on RecA and enhanced in the presence of a DNA-damaging agent, indicating a functional SOS response, but did not result in observable cleavage of the LexA repressor alone, indicating a controlled mechanism of induction. This work demonstrates that environmental factors not usually associated with DNA damage are capable of promoting an SOS-like response. We propose that this modulated induction of RecA allows EHEC to adapt to environmental insults such as D-serine while avoiding unwanted phage-induced lysis.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Roe, Professor Andrew and Connolly, Dr James
Authors: Connolly, J. P.R., and Roe, A. J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Journal of Bacteriology
Publisher:American Society for Microbiology
ISSN:0021-9193
ISSN (Online):1098-5530
Published Online:03 October 2016
Copyright Holders:Copyright © 2016 American Society for Microbiology
First Published:First published in Journal of Bacteriology 198(24): 3318-3328
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
691101Where and Why: The Influence of Host Metabolism on Bacterial Niche SpecificityAndrew RoeBiotechnology and Biological Sciences Research Council (BBSRC)BB/M029646/1III - BACTERIOLOGY