Affiliation:
1. Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands
Abstract
ABSTRACT
Expression of the
pspABCDE
operon of
Escherichia coli
is induced upon infection by filamentous phage and by many other stress conditions, including defects in protein export. Expression of the operon requires the alternative sigma factor σ
54
and the transcriptional activator PspF. In addition, PspA plays a negative regulatory role, and the integral-membrane proteins PspB and PspC play a positive one. In this study, we investigated whether the suggested protein-protein interactions implicated in this complex regulatory network can indeed be demonstrated. Antisera were raised against PspB, PspC, and PspD, which revealed, in Western blotting experiments, that PspC forms stable sodium dodecyl sulfate-resistant dimers and that the hypothetical
pspD
gene is indeed expressed in vivo. Fractionation experiments showed that PspD localizes as a peripherally bound inner membrane protein. Cross-linking studies with intact cells revealed specific interactions of PspA with PspB and PspC, but not with PspD. Furthermore, affinity-chromatography suggested that PspB could bind PspA only in the presence of PspC. These data indicate that regulation of the
psp
operon is mediated via protein-protein interactions.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
62 articles.
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