Nitric oxide reduction, the last step in denitrification by Fusarium oxysporum, is obligatorily mediated by cytochrome P450nor
Nitric oxide reduction, the last step in denitrification by Fusarium oxysporum, is obligatorily mediated by cytochrome P450nor
复制标题
一氧化氮还原是尖镰孢反硝化的最后一步，必须由细胞色素 P450nor 介导
DOI：
10.1007/s004380051177
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
H. Shoun
中科院分区：
文献类型：
--
作者：
N. Takaya;H. Shoun
摘要细胞色素P450 nor（P450 nor）的参与是真菌发酵系统中最显著的特征，而在细菌发酵系统中从未发现过。为了确定P450 nor的生理意义，我们构建并研究了尖孢镰刀菌缺乏P450 nor基因的突变体。我们通过将一个被破坏的基因定向整合到F.尖孢菌属突变体既不含P450，也不含蛋白质，也不含一氧化氮还原酶（Nor）活性，这意味着它们确实缺乏P450或Nor。这些突变体显然已经失去了分解活性，并且在硝酸盐存在下在限氧条件下孵育时不能产生一氧化二氮（N2 O）。他们的菌丝体表现出正常水平的异化亚硝酸还原酶（NIR）的活性，并能够在这些条件下进化NO。将P450 nor基因的启动子区与lacZ融合，并导入F.尖孢菌属转化菌株在发酵条件下产生β-半乳糖苷酶的效率与野生型P450 nor一样。这些结果代表了明确的遗传证据，即P450 nor是F.尖孢菌属
Abstract The involvement of cytochrome P450nor (P450nor) is the most striking feature of the fungal denitrifying system, and has never been shown in bacterial systems. To establish the physiological significance of the P450nor, we constructed and investigated mutants of Fusarium oxysporum that lacked the gene for P450nor. We mutated the gene by targeted integration of a disrupted gene into the chromosome of F. oxysporum. The mutants were shown to contain neither P450nor protein nor nitric oxide (NO) reductase (Nor) activity, implying that they are indeed deficient in P450nor. These mutants had apparently lost the denitrifying activity and failed to evolve nitrous oxide (N2O) upon incubation under oxygen-limiting conditions in the presence of nitrate. Their mycelia exhibited normal levels of dissimilatory nitrite reductase (Nir) activity and were able to evolve NO under these conditions. The promoter region of the P450nor gene was fused to lacZ and introduced into the wild-type strain of F. oxysporum. The transformed strain produced β-galactosidase under denitrifying conditions as efficiently as the wild type does P450nor. These results represent unequivocal genetic evidence that P450nor is essential for the reduction of NO to N2O, the last step in denitrification by F. oxysporum.