2o8v

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spinqualitylabelsall models 2o8v, resolution 3.000Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

PAPS reductase in a covalent complex with thioredoxin C35A

Overview

The 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.

About this Structure

2O8V is a Protein complex structure of sequences from Escherichia coli. Active as Phosphoadenylyl-sulfate reductase (thioredoxin), with EC number 1.8.4.8 Full crystallographic information is available from OCA.

Reference

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):3942-3951. Epub 2007 Mar 13. PMID:17352498

Page seeded by OCA on Wed Nov 21 13:05:22 2007