高等植物中硫酸盐的还原：一种新型5'-腺苷酸硫酸盐还原酶的分子证据。,Proceedings of the National Academy of Sciences of the United States of America

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高等植物中硫酸盐的还原：一种新型5'-腺苷酸硫酸盐还原酶的分子证据。
Proceedings of the National Academy of Sciences of the United States of America ( IF 9.4 ) Pub Date : 1996-11-12 , DOI: 10.1073/pnas.93.23.13383
A Setya ₁ , M Murillo , T Leustek

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硫酸盐同化生物还原无机硫酸盐以进行Cys生物合成。高等植物中硫酸盐还原的机理有两个主要假设。在一种中，腺苷5'-磷酸硫酸盐（APS）（5'-腺苷硫酸盐）磺基转移酶将硫酸盐从APS还原性转移至还原型谷胱甘肽。或者，其机制可能与细菌中的类似，其中3'-磷酸腺苷-5'-磷酸磷酸酯酶（PAPS）还原酶催化硫氧还蛋白（Trx）依赖性的PAPS还原。从拟南芥中克隆了三类cDNA，分别称为APR1，-2和-3，它们在功能上与大肠杆菌的cysH，PAPS还原酶突变株互补。APR克隆的编码序列与来自微生物的PAPS还原酶同源。此外，羧基末端结构域与Trx超家族成员同源。进一步的遗传分析表明，APR克隆可以在功能上补充缺少Trx的大肠杆菌突变株和APS激酶cysC。突变体。这些结果表明，APR酶可能是不依赖Trx的APS还原酶。表达APR的大肠杆菌细胞提取物显示出Trx依赖性的磺核苷酸还原酶活性，相对于PAPS作为底物，APS优先。APR介导的APS还原取决于二硫苏糖醇，最适pH为8.5，受高离子强度刺激，并且对5'-腺苷单磷酸（5'-AMP）的失活敏感。2'-AMP或3'-磷酸腺苷-5'-磷酸（PAP），PAPS还原酶的竞争性抑制剂，不影响活性。APR酶可以定位在不同的细胞区室中，通过APR1和APR3（而非APR2）中质体定位的氨基末端转运肽的存在来证明。Southern印迹分析证实APR克隆是一个小基因家族的成员，可能由三个成员组成。

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Sulfate reduction in higher plants: molecular evidence for a novel 5'-adenylylsulfate reductase.

Sulfate-assimilating organisms reduce inorganic sulfate for Cys biosynthesis. There are two leading hypotheses for the mechanism of sulfate reduction in higher plants. In one, adenosine 5'-phosphosulfate (APS) (5'-adenylysulfate) sulfotransferase carries out reductive transfer of sulfate from APS to reduced glutathione. Alternatively, the mechanism may be similar to that in bacteria in which the enzyme, 3'-phosphoadenosine-5'-phosphosulfate (PAPS) reductase, catalyzes thioredoxin (Trx)-dependent reduction of PAPS. Three classes of cDNA were cloned from Arabidopsis thaliana termed APR1, -2, and -3, that functionally complement a cysH, PAPS reductase mutant strain of Escherichia coli. The coding sequence of the APR clones is homologous with PAPS reductases from microorganisms. In addition, a carboxyl-terminal domain is homologous with members of the Trx superfamily. Further genetic analysis showed that the APR clones can functionally complement a mutant strain of E. coli lacking Trx, and an APS kinase, cysC. mutant. These results suggest that the APR enzyme may be a Trx-independent APS reductase. Cell extracts of E. coli expressing APR showed Trx-independent sulfonucleotide reductase activity with a preference for APS over PAPS as a substrate. APR-mediated APS reduction is dependent on dithiothreitol, has a pH optimum of 8.5, is stimulated by high ionic strength, and is sensitive to inactivation by 5'-adenosinemonophosphate (5'-AMP). 2'-AMP, or 3'-phosphoadenosine-5'-phosphate (PAP), a competitive inhibitor of PAPS reductase, do not affect activity. The APR enzymes may be localized in different cellular compartments as evidenced by the presence of an amino-terminal transit peptide for plastid localization in APR1 and APR3 but not APR2. Southern blot analysis confirmed that the APR clones are members of a small gene family, possibly consisting of three members.

更新日期：2019-11-01

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