Leber hereditary optic neuropathy mutations in the ND6 subunit of mitochondrial complex I affect ubiquinone reduction kinetics in a bacterial model of the enzyme.
Leber hereditary optic neuropathy mutations in the ND6 subunit of mitochondrial complex I affect ubiquinone reduction kinetics in a bacterial model of the enzyme.
复制标题
Leber 遗传性视神经病线粒体复合物 I ND6 亚基的突变影响酶细菌模型中的泛醌还原动力学。
作者：
J. Pätsi;M. Kervinen;M. Finel;I. Hassinen
LHON （Leber遗传性视神经病变）是一种母亲遗传疾病，导致年轻时突然丧失中央视力。有三种常见的初级LHON突变，分别发生在人类mtDNA（线粒体DNA）的3460、11778和14484位，导致线粒体复合体I亚基ND1、ND4和ND6的氨基酸替换。现在，我们利用大肠杆菌NDH-1 （NADH：醌氧化还原酶）的同源NuoJ亚基作为模型系统，研究了ND6突变对复合物I功能的影响。NDH-1突变体的组装水平是通过电子从脱氨基nadh转移到“捷径”电子受体HAR（六检钌）来评估的，而泛醌还原酶活性是用DB（癸二醌）作为底物来确定的。以苹果酸盐为主要碳源的突变体在最小培养基上生长，初步筛选了NDH-1的节能效率。结果表明，NuoJ-M64V（相当于ND6中常见的LHON突变）对大肠杆菌NDH-1活性的影响较轻，而附近的突变，特别是NuoJ-Y59F、NuoJ-V65G和NuoJ-M72V对苹果酸盐的DB还原率和细胞生长严重受损。NuoJ-Met64和NuoJ-Met72位置突变体降低了NDH-1对DB和显性c型抑制剂的亲和力，而NuoJ-Y59C对氧化DB表现出底物抑制作用。结果与ND6亚基描述泛醌底物的结合腔，但不直接参与催化反应的观点一致。讨论了这些酶催化特性的变化如何促进LHON的发病机制。
LHON (Leber hereditary optic neuropathy) is a maternally inherited disease that leads to sudden loss of central vision at a young age. There are three common primary LHON mutations, occurring at positions 3460, 11778 and 14484 in the human mtDNA (mitochondrial DNA), leading to amino acid substitutions in mitochondrial complex I subunits ND1, ND4 and ND6 respectively. We have now examined the effects of ND6 mutations on the function of complex I using the homologous NuoJ subunit of Escherichia coli NDH-1 (NADH:quinone oxidoreductase) as a model system. The assembly level of the NDH-1 mutants was assessed using electron transfer from deamino-NADH to the 'shortcut' electron acceptor HAR (hexammine ruthenium), whereas ubiquinone reductase activity was determined using DB (decylubiquinone) as a substrate. Mutant growth in minimal medium with malate as the main carbon source was used for initial screening of the efficiency of energy conservation by NDH-1. The results indicated that NuoJ-M64V, the equivalent of the common LHON mutation in ND6, had a mild effect on E. coli NDH-1 activity, while nearby mutations, particularly NuoJ-Y59F, NuoJ-V65G and NuoJ-M72V, severely impaired the DB reduction rate and cell growth on malate. NuoJ-Met64 and NuoJ-Met72 position mutants lowered the affinity of NDH-1 for DB and explicit C-type inhibitors, whereas NuoJ-Y59C displayed substrate inhibition by oxidized DB. The results are compatible with the notion that the ND6 subunit delineates the binding cavity of ubiquinone substrate, but does not directly take part in the catalytic reaction. How these changes in the enzyme's catalytic properties contribute to LHON pathogenesis is discussed.
登录
查看更多内容
影响因子：
14.5
作者：
Chinnery, PF;Brown, DT;Howell, N
通讯作者：
Howell, N
使用共价闭合环状质粒 DNA 在大肠杆菌 K-12 中进行基因组替换。
影响因子：
3.5
作者：
Oden,KL;DeVeaux,LC;Vibat,CR;CronanJr,JE;Gennis,RB
通讯作者：
Gennis,RB
影响因子：
9.8
作者：
D. Mackey;N. Howell
通讯作者：
D. Mackey;N. Howell
DOI：
10.1111/j.1432-1033.1994.tb19985.x
发表时间：
1994-01-15
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
FRIEDRICH, T;VANHEEK, P;WEISS, H
通讯作者：
WEISS, H
影响因子：
4.2
作者：
NEWMAN, NJ;LOTT, MT;WALLACE, DC
通讯作者：
WALLACE, DC