Structural insights into the N-terminal GIY-YIG endonuclease activity of Arabidopsis glutaredoxin AtGRXS16 in chloroplasts.Liu, X., Liu, S., Feng, Y., Liu, J.Z., Chen, Y., Pham, K., Deng, H., Hirschi, K.D., Wang, X., Cheng, N.
(2013) Proc.Natl.Acad.Sci.USA 110: 9565-9570
- PubMed: 23690600
- DOI: 10.1073/pnas.1306899110
- PubMed Abstract:
Glutaredoxins (Grxs) have been identified across taxa as important mediators in various physiological functions. A chloroplastic monothiol glutaredoxin, AtGRXS16 from Arabidopsis thaliana, comprises two distinct functional domains, an N-terminal doma ...
Glutaredoxins (Grxs) have been identified across taxa as important mediators in various physiological functions. A chloroplastic monothiol glutaredoxin, AtGRXS16 from Arabidopsis thaliana, comprises two distinct functional domains, an N-terminal domain (NTD) with GlyIleTyr-TyrIleGly (GIY-YIG) endonuclease motif and a C-terminal Grx module, to coordinate redox regulation and DNA cleavage in chloroplasts. Structural determination of AtGRXS16-NTD showed that it possesses a GIY-YIG endonuclease fold, but the critical residues for the nuclease activity are different from typical GIY-YIG endonucleases. AtGRXS16-NTD was able to cleave λDNA and chloroplast genomic DNA, and the nuclease activity was significantly reduced in AtGRXS16. Functional analysis indicated that AtGRXS16-NTD could inhibit the ability of AtGRXS16 to suppress the sensitivity of yeast grx5 cells to oxidative stress; however, the C-terminal Grx domain itself and AtGRXS16 with a Cys123Ser mutation were active in these cells and able to functionally complement a Grx5 deficiency in yeast. Furthermore, the two functional domains were shown to be negatively regulated through the formation of an intramolecular disulfide bond. These findings unravel a manner of regulation for Grxs and provide insights into the mechanistic link between redox regulation and DNA metabolism in chloroplasts.
Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.