Structure-function relationships among the nickel-containing hydrogenases.
Structure-function relationships among the nickel-containing hydrogenases.
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DOI：
10.1111/j.1574-6968.1992.tb04960.x
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发表时间：
1992-02
影响因子：
11.3
通讯作者：
A. Przybyla;Jeffery Robbins;N. Menon;H. D. Peck
中科院分区：
文献类型：
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作者：
A. Przybyla;Jeffery Robbins;N. Menon;H. D. Peck
对异二聚体(NiFe)和(NiFeSe)氢酶、单体含镍氢酶和多聚体F420-(NiFe)和NAD(+)-(NiFe)氢酶的酶学进行了综述，并从氧化还原活性镍和非血红素铁簇的亚基定位方面进行了讨论。有人认为，镍只由大亚基的氨基酸残基连接，非血红素铁簇由氢酶操纵子中编码的其他富含半胱氨酸的多肽连接，这些多肽在结构或功能上都不一定是同源的。氢酶操纵子或可能的操纵子及其氢酶基因的比较表明，除编码大亚基的基因外，这些操纵子中的基因的排列、数量和类型在各种类型的氢酶中并不保守。因此，大亚基基因的存在是所有已知的含镍氢酶的唯一共同特征，并将这些氢酶联合成一个庞大但不同的基因家族。尽管大亚基的不同基因可能只具有名义上的一般衍生氨基酸同源性，但到目前为止测得的所有大亚基基因的序列中，R-X-C-X-X-C序列在多肽链的氨基末端完全保守，D-P-C-X-X-C序列在羧基末端完全保守。有人认为，这些保守的氨基酸基序为氧化还原活性镍的结合提供了所需的配体。总结和讨论了现有的EXAFS(扩展X射线吸收精细结构)信息，包括镍的配体的数量和类型以及由EPR光谱定义的镍的各种氧化还原物种。基于对编码大肠杆菌(NiFe)氢酶-1大亚基的基因的定点突变，提出了有关镍的配体的新信息。在考虑生化、分子和生物物理信息的基础上，提出了镍在(NiFe)氢酶不同氧化还原状态下的配体环境。
The enzymology of the heterodimeric (NiFe) and (NiFeSe) hydrogenases, the monomeric nickel-containing hydrogenases plus the multimeric F420-(NiFe) and NAD(+)-(NiFe) hydrogenases are summarized and discussed in terms of subunit localization of the redox-active nickel and non-heme iron clusters. It is proposed that nickel is ligated solely by amino acid residues of the large subunit and that the non-heme iron clusters are ligated by other cysteine-rich polypeptides encoded in the hydrogenase operons which are not necessarily homologous in either structure or function. Comparison of the hydrogenase operons or putative operons and their hydrogenase genes indicate that the arrangement, number and types of genes in these operons are not conserved among the various types of hydrogenases except for the gene encoding the large subunit. Thus, the presence of the gene for the large subunit is the sole feature common to all known nickel-containing hydrogenases and unites these hydrogenases into a large but diverse gene family. Although the different genes for the large subunits may possess only nominal general derived amino acid homology, all large subunit genes sequenced to date have the sequence R-X-C-X-X-C fully conserved in the amino terminal region of the polypeptide chain and the sequence of D-P-C-X-X-C fully conserved in the carboxyl terminal region. It is proposed that these conserved motifs of amino acids provide the ligands required for the binding of the redox-active nickel. The existing EXAFS (Extended X-ray Absorption Fine Structure) information is summarized and discussed in terms of the numbers and types of ligands to the nickel and the various redox species of nickel defined by EPR spectroscopy. New information concerning the ligands to nickel is presented based on site-directed mutagenesis of the gene encoding the large subunit of the (NiFe) hydrogenase-1 of Escherichia coli. Based on considerations of the biochemical, molecular and biophysical information, ligand environments of the nickel in different redox states of the (NiFe) hydrogenase are proposed.