Journal
RESEARCH IN MICROBIOLOGY
Volume 163, Issue 8, Pages 518-530Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.resmic.2012.07.010
Keywords
Extracytoplasmic stress; CpxA; AckA; Pta; Virulence
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Funding
- Carl Tryggers Foundation for Scientific Research
- Swedish Research Council and the Foundation for Medical Research at Umea University
- Carl Tryggers Post-doctoral fellowship
- UCMR-LP Post-doctoral fellowship
- J C Kempe Memorial Fund
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One way that Gram-negative bacteria respond to extracytoplasmic stress is through the CpxA-CpxR system. An activated CpxA sensor kinase phosphorylates the CpxR response regulator to instigate positive auto-amplification of Cpx pathway activation, as well as synthesis of various bacterial survival factors. In the absence of CpxA, human enteropathogenic Yersinia pseudotuberculosis accumulates high CpxR similar to P levels aided by the action of low molecular weight phosphodonors such as acetyl similar to P. Critically, these bacteria are also defective for plasmid-encoded Ysc-Yop-dependent type III synthesis and secretion, an essential determinant of virulence. Herein, we investigated whether elevated CpxR similar to P levels account for lost Ysc-Yop function. Decisively, reducing CpxR similar to P in Yersinia defective for CpxA phosphatase activity - through incorporating second-site suppressor mutations in ackA-pta or cpxR - dramatically restored Ysc-Yop T3S function. Moreover, the repressive effect of accumulated CpxR similar to P is a direct consequence of binding to the promoter regions of the T3S genes. Thus, Cpx pathway activation has two consequences in Yersinia; one, to maintain quality control in the bacterial envelope, and the second, to restrict ysc-yop gene expression to those occasions where it will have maximal effect. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
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