1v9t
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(New page: 200px<br /><applet load="1v9t" size="450" color="white" frame="true" align="right" spinBox="true" caption="1v9t, resolution 1.70Å" /> '''Structure of E. coli...)
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Revision as of 02:24, 21 November 2007
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Structure of E. coli cyclophilin B K163T mutant bound to succinyl-ALA-PRO-ALA-P-nitroanilide
Overview
Cyclophilins facilitate the peptidyl-prolyl isomerization of a, trans-isomer to a cis-isomer in the refolding process of unfolded proteins, to recover the natural folding state with cis-proline conformation. To, date, only short peptides with a cis-form proline have been observed in, complexes of human and Escherichia coli proteins of cyclophilin A, which, is present in cytoplasm. The crystal structures analyzed in this study, show two complexes in which peptides having a trans-form proline, i.e., succinyl-Ala-trans-Pro-Ala-p-nitroanilide and, acetyl-Ala-Ala-trans-Pro-Ala-amidomethylcoumarin, are bound on a K163T, mutant of Escherichia coli cyclophilin B, the preprotein of which has a, signal sequence. Comparison with cis-form peptides bound to cyclophilin A, reveals that in any case the proline ring is inserted into the hydrophobic, pocket and a hydrogen bond between CO of Pro and Neta2 of Arg is formed to, fix the peptide. On the other hand, in the cis-isomer, the formation of, two hydrogen bonds of NH and CO of Ala preceding Pro with the protein, fixes the peptide, whereas in the trans-isomer formation of a hydrogen, bond between CO preceding Ala-Pro and His47 Nepsilon2 via a mediating, water molecule allows the large distortion in the orientation of Ala of, Ala-Pro. Although loss of double bond character of the amide bond of, Ala-Pro is essential to the isomerization pathway occurring by rotating, around its bond, these peptides have forms impossible to undergo proton, transfer from the guanidyl group of Arg to the prolyl N atom, which, induces loss of double bond character.
About this Structure
1V9T is a Single protein structure of sequence from Escherichia coli. Active as Peptidylprolyl isomerase, with EC number 5.2.1.8 Full crystallographic information is available from OCA.
Reference
Escherichia coli cyclophilin B binds a highly distorted form of trans-prolyl peptide isomer., Konno M, Sano Y, Okudaira K, Kawaguchi Y, Yamagishi-Ohmori Y, Fushinobu S, Matsuzawa H, Eur J Biochem. 2004 Sep;271(18):3794-803. PMID:15355356
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