Zumft W G, Körner H
Lehrstuhl für Mikrobiologie, Universität Fridericiana, Karlsruhe, Germany.
Antonie Van Leeuwenhoek. 1997 Feb;71(1-2):43-58. doi: 10.1023/a:1000112008026.
Denitrification is a main branch of the global nitrogen cycle. In the past ten years unravelling the underlying biochemistry and genetics has proceeded at an increasing pace. Fungal denitrification has become a new field. The biochemical investigation of denitrification has culminated in the description of the crystal structures of the two types of nitrite reductases. The N2O reductase shares with cytochrome c oxidase the CuA center as a structurally novel metal site. The cytochrome b subunit of NO reductase has a striking conservation of heme-binding transmembrane segments versus the subunit I of cytochrome c oxidase. Another putative denitrification gene product shows structural relation to the subunit III of the oxidase. N2O reductase and NO reductase may be ancestors of energy-conserving enzymes of the heme-copper oxidase superfamily. More than 30 genes for denitrification are located in a > 30-kb cluster in Pseudomonas stutzeri, and comparable gene clusters have been identified in Pseudomonas aeruginosa and Paracoccus denitrificans. Genes necessary for nitrite reduction and NO reduction have a mosaic arrangement with very few conserved locations within these clusters and relative to each other.
反硝化作用是全球氮循环的一个主要分支。在过去十年里，对其潜在生物化学和遗传学的研究进展日益加快。真菌反硝化作用已成为一个新领域。反硝化作用的生物化学研究最终得出了两种亚硝酸盐还原酶的晶体结构描述。一氧化二氮还原酶与细胞色素c氧化酶共有CuA中心，作为一种结构新颖的金属位点。一氧化氮还原酶的细胞色素b亚基与细胞色素c氧化酶的亚基I相比，血红素结合跨膜片段具有显著的保守性。另一种假定的反硝化基因产物与氧化酶的亚基III显示出结构关系。一氧化二氮还原酶和一氧化氮还原酶可能是血红素-铜氧化酶超家族中能量保守酶的祖先。在斯氏假单胞菌中，30多个反硝化基因位于一个大于30 kb的基因簇中，在铜绿假单胞菌和反硝化副球菌中也鉴定出了类似的基因簇。亚硝酸盐还原和一氧化氮还原所需的基因呈镶嵌排列，在这些基因簇内以及彼此之间只有很少的保守位置。
