TAILIEUCHUNG - Báo cáo khoa học: The periplasmic peptidyl prolylcis–transisomerases PpiD and SurA have partially overlapping substrate specificities

One of the rate-limiting steps in protein folding has been shown to be the cis–transisomerization of proline residues, catalysed by a range of peptidyl prolylcis–transisomerases (PPIases). In the periplasmic space of Escherichia coliand other Gram-negative bacteria, two PPIases, SurA and PpiD, have been identified, which show high sequence similarity to the catalytic domain of the small PPIase parvulin. | ễFEBS Journal The periplasmic peptidyl prolyl cis-trans isomerases PpiD and SurA have partially overlapping substrate specificities Krista H. Stymest and Peter Klappa Department of Biosciences University of Kent Canterbury UK Keywords peptidyl prolyl cis-trans isomerase periplasmic space protein folding proteinprotein interaction substrate specificities Correspondence P. Klappa Department of Biosciences University of Kent Canterbury CT2 7NJ UK Fax 44 1227 763912 Tel 44 1227 823515 E-mail Received 19 February 2008 revised 14 April2008 accepted 6 May 2008 doi One of the rate-limiting steps in protein folding has been shown to be the cis-trans isomerization of proline residues catalysed by a range of peptidyl prolyl cis-trans isomerases PPIases . In the periplasmic space of Escherichia coli and other Gram-negative bacteria two PPIases SurA and PpiD have been identified which show high sequence similarity to the catalytic domain of the small PPIase parvulin. This observation raises a question regarding the biological significance of two apparently similar enzymes present in the same cellular compartment do they interact with different substrates or do they catalyse different reactions The substrate-binding motif of PpiD has not been characterized so far and no biochemical data were available on how this folding catalyst recognizes and interacts with substrates. To characterize the interaction between model peptides and the periplasmic PPIase PpiD from E. coli we employed a chemical crosslinking strategy that has been used previously to elucidate the interaction of substrates with SurA. We found that PpiD interacted with a range of model peptides independently of whether they contained proline residues or not. We further demonstrate here that PpiD and SurA interact with similar model peptides and therefore must have partially overlapping substrate specificities. However the binding motif of PpiD appears to be less .

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