Clade II nitrous oxide respiration of Wolinella succinogenes depends on the NosG,-C1,-C2, -H electron transport module, NosB and a Rieske/cytochrome bc complex
Clade II nitrous oxide respiration of Wolinella succinogenes depends on the NosG,-C1,-C2, -H electron transport module, NosB and a Rieske/cytochrome bc complex
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DOI：
10.1111/1462-2920.13935
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发表时间：
2017-12-01
影响因子：
5.1
通讯作者：
Simon, Joerg
中科院分区：
文献类型：
--
作者：
Hein, Sascha;Witt, Samantha;Simon, Joerg
微生物还原氧化亚氮（N2O）是生物地球化学氮循环中具有重要环境意义的过程。然而，直到最近才认识到编码N2O还原酶（nosZ）的基因是在不同的遗传背景下组织的，从而定义了进化支I（或典型的）和进化支II（或非典型的）N2O还原酶和nos基因簇。本研究解决了酶学的进化枝II号系统从Wolinella succinogenes, nitrate-ammonifying和N2O-respiring Epsilonproteobacterium包含细胞色素c一氧化二氮还原酶(cNosZ)。单个非极性nos基因缺失突变体的特征表明，NosG、-C1、-C2、-H和-B蛋白是N2O呼吸所必需的。此外，一个琥珀酸w突变体的细胞缺乏一种假定的甲基萘酚氧化Rieske/细胞色素bc复合物（QcrABC），被发现不能呼吸N2O（也不能呼吸硝酸盐）。以甲酸盐为电子供体的N2O呼吸培养的琥珀酸w细胞的摩尔产率比富马酸盐呼吸培养的细胞的摩尔产率高出约30%，这一发现支持了N2O氧化甲基萘酚的质子动机。这一结果要求修订进化枝II N2O呼吸的电子传递链模型，并挑战NosGH（NapGH）型铁硫蛋白对甲基萘酚反应的假设。
Microbial reduction of nitrous oxide (N2O) is an environmentally significant process in the biogeochemical nitrogen cycle. However, it has been recognized only recently that the gene encoding N2O reductase (nosZ) is organized in varying genetic contexts, thereby defining clade I (or typical') and clade II (or atypical') N2O reductases and nos gene clusters. This study addresses the enzymology of the clade II Nos system from Wolinella succinogenes, a nitrate-ammonifying and N2O-respiring Epsilonproteobacterium that contains a cytochrome c N2O reductase (cNosZ). The characterization of single non-polar nos gene deletion mutants demonstrated that the NosG, -C1, -C2, -H and -B proteins were essential for N2O respiration. Moreover, cells of a W. succinogenes mutant lacking a putative menaquinol-oxidizing Rieske/cytochrome bc complex (QcrABC) were found to be incapable of N2O (and also nitrate) respiration. Proton motive menaquinol oxidation by N2O is suggested, supported by the finding that the molar yield for W. succinogenes cells grown by N2O respiration using formate as electron donor exceeded that of fumarate respiration by about 30%. The results demand revision of the electron transport chain model of clade II N2O respiration and challenge the assumption that NosGH(NapGH)-type iron-sulfur proteins are menaquinol-reactive.