3cyi | pdb_00003cyi
Crystal Structure of Human Sulfiredoxin (Srx) in Complex with ATP:Mg2+
Structural highlights
Function[SRXN1_HUMAN] Contributes to oxidative stress resistance by reducing cysteine-sulfinic acid formed under exposure to oxidants in the peroxiredoxins PRDX1, PRDX2, PRDX3 and PRDX4. Does not act on PRDX5 or PRDX6. May catalyze the reduction in a multi-step process by acting both as a specific phosphotransferase and a thioltransferase.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSulfiredoxin (Srx) catalyzes a novel enzymatic reaction, the reduction of protein cysteine sulfinic acid, Cys-SO(2)(-). This reaction is unique to the typical 2-Cys peroxiredoxins (Prx) and plays a role in peroxide-mediated signaling by regulating the activity of Prxs. Two mechanistic schemes have been proposed that differ regarding the first step of the reaction. This step involves either the direct transfer of the gamma-phosphate of ATP to the Prx molecule or through Srx acting as a phosphorylated intermediary. In an effort to clarify this step of the Srx reaction, we have determined the 1.8A resolution crystal structure of Srx in complex with ATP and Mg(2+). This structure reveals the role of the Mg(2+) ion to position the gamma-phosphate toward solvent, thus preventing an in-line attack by the catalytic residue Cys-99 of Srx. A model of the quaternary complex is consistent with this proposal. Furthermore, phosphorylation studies on several site-directed mutants of Srx and Prx, including the Prx-Asp mimic of the Prx-SO(2)(-) species, support a mechanism where phosphorylation of Prx-SO(2)(-) is the first chemical step. Reduction of cysteine sulfinic acid in peroxiredoxin by sulfiredoxin proceeds directly through a sulfinic phosphoryl ester intermediate.,Jonsson TJ, Murray MS, Johnson LC, Lowther WT J Biol Chem. 2008 Aug 29;283(35):23846-51. Epub 2008 Jun 24. PMID:18579529[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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