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Location: Children's Nutrition Research Center

Title: Structure of "Arabidopsis" chloroplastic monothiol glutaredoxin AtGRXcp

item Li, Lenong
item Cheng, Ninghui
item Hirschi, Kendal
item Wang, Xiaoqiang

Submitted to: Acta Crystallographica, Section D: Biological Crystallography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2010
Publication Date: 6/1/2010
Publication URL: http:////
Citation: Li, L., Cheng, NH., Hirschi, K.D., Wang, X. 2010. Structure of "Arabidopsis" chloroplastic monothiol glutaredoxin AtGRXcp. Acta Crystallographica, Section D: Biological Crystallography. D66(Part 6):725-732.

Interpretive Summary: Redox homeostasis is essential for living cells. A group of redox-sensitive proteins, CGFS-type glutaredoxins (Grxs), are important mediators in cellular redox signaling and conserved from bacteria, yeast, plants to human. However, the molecular and structural basis underlying this mechanism is still scant. In this study, the CNRC scientist has for the first time defined the crystal structure of a CFGS-type Grx that was identified from a model plant, "Arabidopsis thaliana". This study discovered a key structural feature for this group of redox proteins and provided the first structural information on CGFS-type Grxs that allows a better understanding of the redox-regulation mechanism mediated by this novel group of Grxs.

Technical Abstract: Monothiol glutaredoxins (Grxs) play important roles in maintaining redox homeostasis in living cells and are conserved across species. "Arabidopsis thaliana" monothiol glutaredoxin AtGRXcp, is critical for protection from oxidative stress in chloroplasts. The crystal structure of AtGRXcp has been determined at 2.4 A resolution. AtGRXcp has a glutaredoxin/thioredoxin-like fold with distinct structural features that differ from those of dithiol Grxs. The structure reveals that the putative active-site motif CGFS is well defined and is located on the molecular surface and that a long groove extends to both sides of the catalytic Cys97. Structural comparison and molecular modeling suggest that glutathione can bind in this groove and form extensive interactions with conserved charged residues including Lys89, Arg126 and Asp152. Further comparative studies reveal that a unique loop with five additional residues adjacent to the active-site motif may be a key structural feature of monothiol Grxs and may influence their function. This study provides the first structural information on plant CGFS-type monothiol Grxs, allowing a better understanding of the redox-regulation mechanism mediated by these plant Grxs.