1u79
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(New page: 200px<br /><applet load="1u79" size="450" color="white" frame="true" align="right" spinBox="true" caption="1u79, resolution 1.85Å" /> '''Crystal structure of...)
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Revision as of 01:46, 21 November 2007
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Crystal structure of AtFKBP13
Overview
Change in redox status has long been known to link light to the, posttranslational regulation of chloroplast enzymes. So far, studies have, been conducted primarily with thioredoxin-linked members of the stroma, that function in a broad array of biosynthetic and degradatory processes., Consequently, little is known about the role of redox in regulating the, growing number of enzymes found to occur in the lumen, the site of oxygen, evolution in thylakoid membranes. To help fill this gap, we have studied, AtFKBP13, an FKBP-type immunophilin earlier shown to interact with a, redox-active protein of the lumen, and found the enzyme to contain a pair, of disulfide bonds in x-ray structural studies. These disulfides, which in, protein mutagenesis experiments were shown to be essential for the, associated peptidyl-prolyl isomerase activity, are unique to chloroplast, FKBPs and are absent in animal and yeast counterparts. Both disulfide, bonds were redox-active and were reduced by thioredoxin from either, chloroplast or bacterial sources in a reaction that led to loss of enzyme, activity. The results suggest a previously unrecognized paradigm for redox, regulation in chloroplasts in which activation by light is achieved in, concert with oxygen evolution by the oxidation of sulfhydryl groups, (conversion of SH to S-S). Such a mechanism, occurring in the thylakoid, lumen, is in direct contrast to regulation of enzymes in the stroma, where, reduction of disulfides targeted by thioredoxin (S-S converted to SH), leads to an increase in activity in the light.
About this Structure
1U79 is a Single protein structure of sequence from Arabidopsis thaliana. Active as Peptidylprolyl isomerase, with EC number 5.2.1.8 Full crystallographic information is available from OCA.
Reference
Structural analysis uncovers a role for redox in regulating FKBP13, an immunophilin of the chloroplast thylakoid lumen., Gopalan G, He Z, Balmer Y, Romano P, Gupta R, Heroux A, Buchanan BB, Swaminathan K, Luan S, Proc Natl Acad Sci U S A. 2004 Sep 21;101(38):13945-50. Epub 2004 Sep 8. PMID:15356344
Page seeded by OCA on Wed Nov 21 03:53:37 2007
