Rothery Richard A, Workun Gregory J, Weiner Joel H
Membrane Protein Research Group, Department of Biochemistry, 474 Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.
Biochim Biophys Acta. 2008 Sep;1778(9):1897-929. doi: 10.1016/j.bbamem.2007.09.002. Epub 2007 Sep 18.
Bacterial genomes encode an extensive range of respiratory enzymes that enable respiratory metabolism with a diverse group of reducing and oxidizing substrates under both aerobic and anaerobic growth conditions. An important class of enzymes that contributes to this broad diversity is the complex iron-sulfur molybdoenzyme (CISM) family. The architecture of this class comprises the following subunits. (i) A molybdo-bis(pyranopterin guanine dinucleotide) (Mo-bisPGD) cofactor-containing catalytic subunit that also contains a cubane [Fe-S] cluster (FS0). (ii) A four-cluster protein (FCP) subunit that contains 4 cubane [Fe-S] clusters (FS1-FS4). (iii) A membrane anchor protein (MAP) subunit which anchors the catalytic and FCP subunits to the cytoplasmic membrane. In this review, we define the CISM family of enzymes on the basis of emerging structural and bioinformatic data, and show that the catalytic and FCP subunit architectures appear in a wide range of bacterial redox enzymes. We evaluate evolutionary events involving genes encoding the CISM catalytic subunit that resulted in the emergence of the complex I (NADH:ubiquinone oxidoreductase) Nqo3/NuoG subunit architecture. We also trace a series of evolutionary events leading from a primordial Cys-containing peptide to the FCP architecture. Finally, many of the CISM archetypes and related enzymes rely on the tat translocon to transport fully folded monomeric or dimeric subunits across the cytoplasmic membrane. We have used genome sequence data to establish that there is a bias against the presence of soluble periplasmic molybdoenzymes in bacteria lacking an outer membrane.
细菌基因组编码了广泛的呼吸酶，这些酶能够在有氧和无氧生长条件下，利用多种还原和氧化底物进行呼吸代谢。对这种广泛多样性有重要贡献的一类酶是复杂铁硫钼酶（CISM）家族。这类酶的结构由以下亚基组成。（i）一个含钼双（吡喃蝶呤鸟嘌呤二核苷酸）（Mo-bisPGD）辅因子的催化亚基，该亚基还含有一个立方烷型[Fe-S]簇（FS0）。（ii）一个四簇蛋白（FCP）亚基，其包含4个立方烷型[Fe-S]簇（FS1-FS4）。（iii）一个膜锚定蛋白（MAP）亚基，它将催化亚基和FCP亚基锚定到细胞质膜上。在本综述中，我们基于新出现的结构和生物信息学数据定义了CISM酶家族，并表明催化亚基和FCP亚基结构出现在广泛的细菌氧化还原酶中。我们评估了涉及编码CISM催化亚基的基因的进化事件，这些事件导致了复合体I（NADH：泛醌氧化还原酶）Nqo3/NuoG亚基结构的出现。我们还追溯了从原始含半胱氨酸肽到FCP结构的一系列进化事件。最后，许多CISM原型和相关酶依赖于tat转运体将完全折叠的单体或二聚体亚基转运穿过细胞质膜。我们利用基因组序列数据确定，在缺乏外膜的细菌中，可溶性周质钼酶的存在存在偏向性。
