2o8v
From Proteopedia
PAPS reductase in a covalent complex with thioredoxin C35A
Structural highlights
FunctionCYSH_ECOLI Reduction of activated sulfate into sulfite.[HAMAP-Rule:MF_00063] Evolutionary ConservationCheck, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe crystal structure of Escherichia coli 3'-phosphoadenosine-5'-phosphosulfate (PAPS) reductase in complex with E. coli thioredoxin 1 (Trx1) has been determined to 3.0 A resolution. The two proteins are covalently linked via a mixed disulfide that forms during nucleophilic attack of Trx's N-terminal cysteine on the Sgamma atom of the PAPS reductase S-sulfocysteine (E-Cys-Sgamma-SO3-), a central intermediate in the catalytic cycle. For the first time in a crystal structure, residues 235-244 in the PAPS reductase C-terminus are observed, depicting an array of interprotein salt bridges between Trx and the strictly conserved glutathione-like sequence, Glu238Cys239Gly240Leu241His242. The structure also reveals a Trx-binding surface adjacent to the active site cleft and regions of PAPS reductase associated with conformational change. Interaction at this site strategically positions Trx to bind the S-sulfated C-terminus and addresses the mechanism for requisite structural rearrangement of this domain. An apparent sulfite-binding pocket at the protein-protein interface explicitly orients the S-sulfocysteine Sgamma atom for nucleophilic attack in a subsequent step. Taken together, the structure of PAPS reductase in complex with Trx highlights the large structural rearrangement required to accomplish sulfonucleotide reduction and suggests a role for Trx in catalysis beyond the paradigm of disulfide reduction. 3'-Phosphoadenosine-5'-phosphosulfate reductase in complex with thioredoxin: a structural snapshot in the catalytic cycle.,Chartron J, Shiau C, Stout CD, Carroll KS Biochemistry. 2007 Apr 3;46(13):3942-51. Epub 2007 Mar 13. PMID:17352498[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
|