Interaction of the Periplasmic Peptidylprolylcis-trans Isomerase SurA with Model Peptides
THE N-TERMINAL REGION OF SurA IS ESSENTIAL AND SUFFICIENT FOR PEPTIDE BINDING*
- From the University of Kent, Canterbury CT2 7NJ, United Kingdom and‡Biocenter Oulu and the Department of Biochemistry, Oulu FIN-90014, Finland
Abstract
One of the rate-limiting steps in protein folding has been shown to be the cis-trans isomerization of proline residues, which is catalyzed by a range of peptidylprolylcis-trans isomerases. To characterize the interaction between model peptides and the periplasmic peptidylprolylcis-trans isomerase SurA from E. coli, we employed a chemical cross-linking strategy that has been used previously to elucidate the interaction of substrates with other folding catalysts. The interaction between purified SurA and model peptides was significant in that it showed saturation and was abolished by denaturation of SurA; however the interaction was independent of the presence of proline residues in the model peptides. From results obtained by limited proteolysis we conclude that an N-terminal fragment of SurA, comprising 150 amino acids that do not contain the active sites involved in the peptidylprolyl cis-transisomerization, is essential for the binding of peptides by SurA. This was confirmed by probing the interaction of the model peptide with the recombinant N-terminal fragment, expressed in Escherichia coli. Hence we propose that, similar to protein disulfide isomerase and other folding catalysts, SurA exhibits a modular architecture composed of a substrate binding domain and distinct catalytically active domains.
Footnotes
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↵* This work was supported by Biotechnology and Biological Sciences Research Council Grant 96/C10318 (to L. W. R. and Robert B. Freedman) and a Wellcome Trust summer studentship (to R. J. M.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵§ To whom correspondence should be addressed. Tel.: 44-1227-823515; Fax: 44-1227-763912; E-mail: P.Klappa@ukc.ac.uk.
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Published, JBC Papers in Press, August 23, 2001, DOI 10.1074/jbc.M107508200
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↵2 L. W. Ruddock, unpublished results.
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↵3 K. Ramm and A. Plückthun, personal communication.
- Abbreviations:
- PDI
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protein disulfide isomerase
- PPIase
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peptidylprolyl cis-transisomerase
- DSG
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disuccinimidyl glutarate
- PMSF
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phenylmethylsulfonyl fluoride
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- Received August 6, 2001.
- Revision received August 23, 2001.
- The American Society for Biochemistry and Molecular Biology, Inc.
