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J. Biol. Chem., Vol. 283, Issue 14, 8868-8876, April 4, 2008

This Article Full Text Full Text (PDF) All Versions of this Article: 283/14/8868    most recent M709567200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Zaffagnini, M. Articles by Lemaire, S. D. PubMed PubMed Citation Articles by Zaffagnini, M. Articles by Lemaire, S. D. Social Bookmarking                      What's this?

Biochemical Characterization of Glutaredoxins from Chlamydomonas reinhardtii Reveals the Unique Properties of a Chloroplastic CGFS-type Glutaredoxin^*

Mirko Zaffagnini, Laure Michelet, Vincent Massot, Paolo Trost, and Stéphane D. Lemaire¹

From the Institut de Biotechnologie des Plantes, UMR 8618, CNRS/University of Paris-Sud 11, Bâtiment 630, Orsay 91405, Cedex, France and the Laboratory of Molecular Plant Physiology, Department of Experimental Evolutionary Biology, University of Bologna, Via Irnerio 42, Bologna 40126, Italy

Glutaredoxins (GRXs) are small ubiquitous disulfide oxidoreductases known to use GSH as electron donor. In photosynthetic organisms, little is known about the biochemical properties of GRXs despite the existence of 30 different isoforms in higher plants. We report here the biochemical characterization of Chlamydomonas GRX1 and GRX3, the major cytosolic and chloroplastic isoforms, respectively. Glutaredoxins are classified on the basis of the amino acid sequence of the active site. GRX1 is a typical CPYC-type GRX, which is reduced by GSH and exhibits disulfide reductase, dehydroascorbate reductase, and deglutathionylation activities. In contrast, GRX3 exhibits unique properties. This chloroplastic CGFS-type GRX is not reduced by GSH and has an atypically low redox potential (–323 ± 4 mV at pH 7.9). Remarkably, GRX3 can be reduced in the light by photoreduced ferredoxin and ferredoxin-thioredoxin reductase. Both GRXs proved to be very efficient catalysts of A₄-glyceraldehyde-3-phosphate dehydrogenase deglutathionylation, whereas cytosolic and chloroplastic thioredoxins were inefficient. Glutathionylated A₄-glyceraldehyde-3-phosphate dehydrogenase is the first physiological substrate identified for a CGFS-type GRX.

Received for publication, November 21, 2007 , and in revised form, January 23, 2008.

^* This work was supported by the Agence Nationale de la Recherche (Grant JC-45751) and by the Italian Ministry of University (Grants FIRB 2003 and PRIN 2005). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed. Tel.: 33-1-69-15-33-38; Fax: 33-1-69-15-34-24; E-mail: stephane.lemaire{at}u-psud.fr.

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