BIOCHEMICAL-CHARACTERIZATION OF THE MOLYBDENUM COFACTOR MUTANTS OF NEUROSPORA-CRASSA - INVIVO AND INVITRO RECONSTITUTION OF NADPH-NITRATE REDUCTASE-ACTIVITY
BIOCHEMICAL-CHARACTERIZATION OF THE MOLYBDENUM COFACTOR MUTANTS OF NEUROSPORA-CRASSA - INVIVO AND INVITRO RECONSTITUTION OF NADPH-NITRATE REDUCTASE-ACTIVITY
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DOI：
10.1007/bf00395703
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发表时间：
1984-01-01
期刊：
影响因子：
2.5
通讯作者：
DUNNCOLEMAN, NS
中科院分区：
文献类型：
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作者：
DUNNCOLEMAN, NS
粗糙脉孢菌的 Mol 辅因子 (MoCo) 突变体缺乏 NADPH 硝酸还原酶和黄嘌呤脱氢酶活性。现在报道了进一步表征这些突变体的体内和体外研究。如果存在高水平的钼酸盐，MoCo 突变体 nit-9A 和 nit-9B 能够以硝酸盐作为唯一的氮源生长，尽管生长很差。当在含有 30 mM 钼酸盐的硝酸盐培养基中生长时，MoCo 突变体 nit-9A、nit-9B 和 nit-9C（但不是 nit-1、nit-7 或 nit-8）具有显着水平的 NADPH-硝酸还原酶。使用粗糙链孢霉 MoCo 突变体的无细胞提取物和大肠杆菌 HB101 作为野生型 MoCo 来源进行了体外重建实验。来自大肠杆菌的 MoCo 能够将 NADPH 硝酸还原酶活性重建为 nit-1、nit-7 和 nit-8。 NADPH-硝酸还原酶活性的体外重建需要钼酸盐。不可能在 MoCo 突变体 nit-9、nit-9B 或 nit-9C 中体外重建 NADPH-硝酸还原酶活性。
Mol cofactor (MoCo) mutants of N. crassa lack NADPH-nitrate reductase and xanthine dehydrogenase activity. In vivo and in vitro studies to further characterize these mutants are now reported. The MoCo mutants nit-9A and nit-9B are capable of growing, albeit poorly, with nitrate as the sole N source, provided high levels of molybdate are present. The MoCo mutants nit-9A, nit-9B and nit-9C, but not nit-1, nit-7 or nit-8, have significant levels of NADPH-nitrate reductase when grown in nitrate medium containing 30 mM molybdate. In vitro reconstitution experiments using cell-free extracts of the N. crassa MoCo mutants and Escherichia coli HB101 as a source of wild-type MoCo were performed. MoCo from E. coli was capable of reconstituting NADPH-nitrate reductase activity to nit-1, nit-7 and nit-8. Molybdate is required for the in vitro reconstitution of NADPH-nitrate reductase activity. It was not possible to in vitro reconstitute NADPH-nitrate reductase activity in the MoCo mutants nit-9, nit-9B or nit-9C.