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3‘-Phosphoadenosine-5‘-phosphosulfate Reductase in Complex with Thioredoxin: A Structural Snapshot in the Catalytic Cycle

Chartron, Justin and Shiau, Carrie and Stout, C. David and Carroll, Kate S. (2007) 3‘-Phosphoadenosine-5‘-phosphosulfate Reductase in Complex with Thioredoxin: A Structural Snapshot in the Catalytic Cycle. Biochemistry, 46 (13). pp. 3942-3951. ISSN 0006-2960. PMCID PMC3109433. doi:10.1021/bi700130e.

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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 Å resolution. The two proteins are covalently linked via a mixed disulfide that forms during nucleophilic attack of Trx's N-terminal cysteine on the Sγ atom of the PAPS reductase S-sulfocysteine (E-Cys-Sγ-SO_3^-), 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, Glu^(238)Cys^(239)Gly^(240)Leu^(241)His^(242). 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 Sγ 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.

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Additional Information:© 2007 American Chemical Society. Received 23 January 2007. Published online 13 March 2007. Published in print 1 April 2007. This work was supported by National Institutes of Health Grants GM-48870 and AI-51622. K.S.C. was supported by a postdoctoral fellowship from the Damon Runyon Cancer Research Foundation (DRG-1783-03) and by funding from the University of Michigan Life Sciences Institute. We thank Profs. Janet Smith, Rowena Matthews, and Carolyn Bertozzi for many helpful discussions. We thank the generous assistance of the staff at the Stanford Synchrotron Radiation Laboratory (SSRL). SSRL is a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. The SSRL Structural Molecular Biology Program is supported by the Department of Energy, Office of Biological and Environmental Research, and by the National Institutes of Health, National Center for Research Resources, Biomedical Technology Program, and the National Institute of General Medical Sciences.
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Damon Runyon Cancer Research FoundationDRG-1783-03
University of MichiganUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
National Institute of General Medical SciencesUNSPECIFIED
Issue or Number:13
PubMed Central ID:PMC3109433
Record Number:CaltechAUTHORS:20170201-074622080
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Official Citation:3‘-Phosphoadenosine-5‘-phosphosulfate Reductase in Complex with Thioredoxin:  A Structural Snapshot in the Catalytic Cycle, Justin Chartron, Carrie Shiau, C. David Stout, and Kate S. Carroll Biochemistry 2007 46 (13), 3942-3951 DOI: 10.1021/bi700130e
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73904
Deposited By: Ruth Sustaita
Deposited On:01 Feb 2017 16:53
Last Modified:11 Nov 2021 05:23

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