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首页> 外文期刊>Biochemistry >3'-Phosphoadenosine-5'-phosphosulfate reductase in complex with thioredoxin: a structural snapshot in the catalytic cycle.
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3'-Phosphoadenosine-5'-phosphosulfate reductase in complex with thioredoxin: a structural snapshot in the catalytic cycle.

机译：3'-磷烯苷-5'-磷硫酸盐还原酶复合物与硫氧吡啶：催化循环中的结构快照。

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摘要

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.
机译：将大肠杆菌3'-氟磺酸钠-5'-磷磺酸氢酸酯-5-磷磺酸盐（PAPS）还原酶的晶体结构与大肠杆菌硫氧嗪1（TRX1）确定为3.0分辨率。两种蛋白质通过混合二硫化物共价连接，所述混合二硫化硫化物在Trx的N-末端半胱氨酸的亲核侵袭期间形成PAPS还原酶S-磺脲类（E-CYS-SGAMMA-SO3-），中间中间体在催化循环中的中间体。对于第一次在晶体结构中，观察到PAPS还原酶C-末端中的残基235-244，描绘了TRX和严格保守的谷胱甘肽样序列之间的译文阵列，GLU238CYS239GLY240LEU241HIS242。该结构还揭示了与有效位点裂缝和与构象变化相关的PAPS还原酶区域相邻的Trx结合表面。在本网站的互动策略性地定位TRX绑定S-硫酸化的C-Terminus并解决了该域的必要结构重排的机制。在蛋白质 - 蛋白质界面处的表观亚硫酸盐结合口袋明确地或者在随后的步骤中明确地是用于亲硫氰酸叔氏菌原子的S-硫纤维蛋白。占据在一起，与TRX复合物中的PAPS还原酶的结构突出了完成硫核苷酸降低所需的大结构重排，并表明TRX在催化超出二硫化物降低范式的催化作用。

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