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Infect. Immun., 06 1997, 2190-2196, Vol 65, No. 6
T Yamamoto, T Hanawa, S Ogata and S Kamiya
The Yersinia enterocolitica gsrA gene is a stress protein gene which was
originally identified as essential for protecting cells under both
extracellular environmental stress and intracellular stress in macrophages
due to phagocytosis. The gsrA gene was shown to be a member of the htrA
class of genes and to possess a sequence homologous to that of the promoter
recognized by a stress-induced sigma factor, sigmaE. In order to study the
induction of the potentially sigmaE-controlled gsrA gene in Y.
enterocolitica after phagocytosis by macrophages, we identified GsrA by
overproducing the protein using a T7 promoter-gsrA fusion. We found that it
is translated as an unstable 49,500-Da protein which is processed by
removal of an amino acid fragment consisting of 27 residues, resulting in a
stable 46,800-Da protein. By radiolabeling proteins specific to bacteria in
the J774-1 macrophage-like cell line, we found that the production of GsrA
protein is indeed enhanced in bacterial cells growing within macrophage
phagosomes. Transcriptional activation of the gsrA gene was determined by
using the gsrA promoter- lacZ fusion system. This work provides the first
piece of evidence that the sigmaE regulon responds to the stressful
environment found in macrophages.
Copyright © 1997, American Society for Microbiology
The Yersinia enterocolitica GsrA stress protein, involved in intracellular survival, is induced by macrophage phagocytosis
Department of Microbiology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan. tmky-bac@tt.rim.or.jp
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