Identification of a new class of 5′-adenylylsulfate (APS) reductases from sulfate-assimilating bacteria
Identification of a new class of 5′-adenylylsulfate (APS) reductases from sulfate-assimilating bacteria
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DOI：
10.1128/jb.182.1.135-142.2000
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发表时间：
2000-01-01
影响因子：
3.2
通讯作者：
Leustek, T
中科院分区：
文献类型：
--
作者：
Bick, JA;Dennis, JJ;Leustek, T
从洋葱伯克霍尔德氏菌DBO 1中克隆了一个与大肠杆菌cysH同源的基因，该基因编码3 '-磷酸腺苷酰硫酸（PAPS）还原酶。B。cepacia基因是最近加入的一个不断增长的硫酸盐同化细菌的cysH同源物的列表，其产物与植物5 '-腺苷酰硫酸（APS）还原酶的同源性比与大肠杆菌的同源性更高。coliCysH，本文报道的证据表明，铜绿假单胞菌（Pseudomonasaeruginosa）的CysH编码APS还原酶，它能与大肠杆菌的CysH互补。colicysH突变体和cysC突变体，表明该酶能够绕过PAPS，由cysC产物合成。铜绿假单胞菌cysH的插入敲除突变产生半胱氨酸营养缺陷型，表明其在硫酸盐同化中的作用。纯化的铜绿假单胞菌CysH表达为His标记的重组蛋白，其能够还原APS，但不能还原PAPS，该酶的比活性为5.8 μ mol . min（-1）。在pH 8.5和30 ° C下，以硫氧还蛋白作为电子供体，APS还原酶的活性检测在几种细菌物种的新型cysH已被克隆，表明这种酶可能是广泛的。虽然已知来自异化硫酸盐还原菌的APS还原酶，但它与本文报道的同化型APS还原酶没有结构或序列同源性。结果表明，异化和同化APS还原酶的进化趋同。
A gene was cloned from Burkholderia cepacia DBO1 that is homologous with Escherichia coli cysH encoding 3'-phosphoadenylylsulfate (PAPS) reductase. The B. cepacia gene is the most recent addition to a growing list of cysH homologs from a diverse group of sulfate-assimilating bacteria whose products show greater homology to plant 5'-adenylylsulfate (APS) reductase than they do to E. coli CysH, The evidence reported here shows that the cysH from one of the species, Pseudomonas aeruginosa, encodes APS reductase, It is able to complement an E. coli cysH mutant and a cysC mutant, indicating that the enzyme is able to bypass PAPS, synthesized by the cysC product. Insertional knockout mutation of P. aeruginosa cysH produced cysteine auxotrophy, indicating its role in sulfate assimilation. Purified P, aeruginosa CysH expressed as a His-tagged recombinant protein is able to reduce APS, but not PAPS, The enzyme has a specific activity of 5.8 mu mol . min(-1) . mg of protein(-1) at pH 8.5 and 30 degrees C with thioredoxin supplied as an electron donor. APS reductase activity was detected in several bacterial species from which the novel type of cysH has been cloned, indicating that this enzyme may be widespread. Although an APS reductase from dissimilatory sulfate-reducing bacteria is known, it shows no structural or sequence homology with the assimilatory-type APS reductase reported here. The results suggest that the dissimilatory and assimilatory APS reductases evolved convergently.