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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
1
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pubmed:dateCreated |
2006-12-7
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pubmed:abstractText |
Cyps (cyclophilins) are ubiquitous proteins of the immunophilin superfamily with proposed functions in protein folding, protein degradation, stress response and signal transduction. Conserved cysteine residues further suggest a role in redox regulation. In order to get insight into the conformational change mechanism and functional properties of the chloroplast-located CYP20-3, site-directed mutagenized cysteine-->serine variants were generated and analysed for enzymatic and conformational properties under reducing and oxidizing conditions. Compared with the wild-type form, elimination of three out of the four cysteine residues decreased the catalytic efficiency of PPI (peptidyl-prolyl cis-trans isomerase) activity of the reduced CYP20-3, indicating a regulatory role of dithiol-disulfide transitions in protein function. Oxidation was accompanied by conformational changes with a predominant role in the structural rearrangement of the disulfide bridge formed between Cys(54) and Cys(171). The rather negative E(m) (midpoint redox potential) of -319 mV places CYP20-3 into the redox hierarchy of the chloroplast, suggesting the activation of CYP20-3 in the light under conditions of limited acceptor availability for photosynthesis as realized under environmental stress. Chloroplast Prx (peroxiredoxins) were identified as interacting partners of CYP20-3 in a DNA-protection assay. A catalytic role in the reduction of 2-Cys PrxA and 2-Cys PrxB was assigned to Cys(129) and Cys(171). In addition, it was shown that the isomerization and disulfide-reduction activities are two independent functions of CYP20-3 that both are regulated by the redox state of its active centre.
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pubmed:commentsCorrections |
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Jan
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pubmed:issn |
1470-8728
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pubmed:author |
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pubmed:issnType |
Electronic
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pubmed:day |
1
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pubmed:volume |
401
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
287-97
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:16928193-Arabidopsis,
pubmed-meshheading:16928193-Arabidopsis Proteins,
pubmed-meshheading:16928193-Cyclophilins,
pubmed-meshheading:16928193-Cysteine,
pubmed-meshheading:16928193-Genetic Variation,
pubmed-meshheading:16928193-Kinetics,
pubmed-meshheading:16928193-Mutagenesis, Site-Directed,
pubmed-meshheading:16928193-RNA, Plant,
pubmed-meshheading:16928193-Recombinant Proteins
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pubmed:year |
2007
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pubmed:articleTitle |
Role of the cysteine residues in Arabidopsis thaliana cyclophilin CYP20-3 in peptidyl-prolyl cis-trans isomerase and redox-related functions.
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pubmed:affiliation |
Biochemistry and Physiology of Plants, Faculty of Biology, W5, Bielefeld University, 33501 Bielefeld, Germany.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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