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Title: Redox regulation: Roles of an Arabidopsis chloroplastic monothiol glutaredoxin

Author
item CHENG, NING-HUI - BAYLOR COLL OF MEDICINE
item BROCK, AMANDA - BAYLOR COLL OF MEDICINE
item Hirschi, Kendal

Submitted to: Joint Meeting of the American Society of Plant Biologists and the Canadian Society of Plant Physiologists
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2006
Publication Date: 8/5/2006
Citation: Cheng, N-H., Brock, A., Hirschi, K.D. 2006. Redox regulation: Roles of an Arabidopsis chloroplastic monothiol glutaredoxin [abstract]. The Joint Annual Meeting of the American Society of Plant Biologists and the Canadian Society of Plant Physiologist, August 5-9, 2006, Boston, Massachusetts. Session P07: Oxidative Stress, Abstract P07003, p. 131.

Interpretive Summary:

Technical Abstract: Redox states in all biological systems including plants are thought to play vital roles in maintaining and/or regulating cellular processes and metabolisms in response to extreme conditions, such as oxidative stresses, nutritional perturbation, and metabolic disorders. There is a growing body of evidence that Glutaredoxins (Grxs), along with glutathione (GSH) and GSH reductase, may play critical roles in regulating the thiol group of proteins. Recently, PICOT-HD containing proteins (Protein kinase C Interacting Cousin Of Thioredoxin Homology Domain) were identified as monothiol glutaredoxins (Grxs) that are conserved in both prokaryotes and eukaryotes. Preliminary investigations on PICOT-HD Grxs suggest that those proteins may have critical roles in protecting cells against oxidative damages. However, the actual biological functions of PICOT-HD Grxs have not been fully studied in any organism. Here we demonstrate that a plant PICOT-HD containing protein, AtGRXcp, is a chloroplast/plastid-localized monothiol Grx. In yeast expression assays, AtGRXcp localized to the mitochondria and partially suppressed the sensitivity of yeast cells to H[2]O[2] and protein oxidation. Mutation of an evolutionarily conserved cysteine residue drastically affected protein stability. In planta, AtGRXcp expression was high in young cotyledons, green tissues and vascular bundles. Analysis of AtGRXcp null alleles demonstrated defects in early seedling growth under oxidative stresses. In addition, atgrxcp lines displayed increased protein carbonylation in chloroplasts/plastids. Thus, these findings suggest a conserved biological function among monothiol Grxs in protecting cells from protein oxidative damage and adapting organisms to external stresses.