title: Interaction of the periplasmic peptidylprolyl cis-trans isomerase SurA with model peptides. The N-terminal region of SurA id essential and sufficient for peptide binding.
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 peptidylprolyl cis-trans isomerases. To characterize the interaction between model peptides and the periplasmic peptidylprolyl cis-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-trans isomerization, 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.
authors.affiliation: University of Kent, Canterbury CT2 7NJ, United Kingdom.
authors.forename: H M
authors.initials: HM
authors.lastname: Webb
authors.forename: L W
authors.initials: LW
authors.lastname: Ruddock
authors.forename: R J
authors.initials: RJ
authors.lastname: Marchant
authors.forename: K
authors.initials: K
authors.lastname: Jonas
authors.forename: P
authors.initials: P
authors.lastname: Klappa
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins; D003001:Cloning, Molecular; D017931:DNA Primers; D029968:Escherichia coli Proteins; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism*; D019696:Peptidylprolyl Isomerase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019897:Periplasm / Q000201:enzymology*; D011485:Protein Binding; D013004:Somatostatin / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D010455:Peptides; D013004:Somatostatin; C490900:SurA protein, E coli; C098640:periplasmic peptidylprolyl cis-trans isomerase; D019696:Peptidylprolyl Isomerase