Cytochrome oxidase genes from Thermus thermophilus. Nucleotide sequence of the fused gene and analysis of the deduced primary structures for subunits I and III of cytochrome caa3.
Cytochrome oxidase genes from Thermus thermophilus. Nucleotide sequence of the fused gene and analysis of the deduced primary structures for subunits I and III of cytochrome caa3.
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DOI：
10.1016/s0021-9258(18)53335-4
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发表时间：
1993-03
期刊：
影响因子：
--
通讯作者：
M. Mather;P. Springer;S. Hensel;G. Buse;J. Fee
中科院分区：
文献类型：
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作者：
M. Mather;P. Springer;S. Hensel;G. Buse;J. Fee
细胞色素Caa3是一种来自Thermus thermophilus的细胞色素c氧化酶，已被纯化并被广泛鉴定为含有细胞色素c氧化酶的金属中心(细胞色素a和A3；铜中心CuA和Cub)和额外的细胞色素c(Fee，J.A.，Kuila，D.，Mather，M.W.和Yoshida，T.(1986)Biochim)。生物群落。学报853、153-185)。我们现在已经克隆了这种酶的亚单位的编码基因并进行了测序。较小的亚基由融合到细胞色素c结构域的典型的氧化酶亚基II序列组成(Mather，M.W.，Springer，P.和Fee，J.A.(1991)J.Biol)。化学。266、5025-5035)。较大的亚基A蛋白由紧邻IIc亚基下游的融合基因编码。该基因5‘端编码一个亚基I，而3’端编码一个亚基III。从纯化的酶中分离出的A蛋白，从SDS-PAGE和氨基酸定量分析来看，似乎太小，不是一个完整的亚基I/III融合，但目前尚不清楚是否发生了蛋白水解性加工。对氧化物酶亚基序列的分析清楚地表明，嗜热梭菌细胞色素Caa3是需要血红素和铜的氧化酶大家族中真正的成员。一个结果是，证实了细胞色素C氧化酶亚基I和II中的不变组氨酸残基(金属中心的潜在配体)减少到8个。基于同源性、疏水性和可变性的考虑，建立了可能的拓扑和螺旋堆积模型。
Cytochrome caa3, a cytochrome c oxidase from Thermus thermophilus, has been purified and extensively characterized as a two-subunit enzyme containing the metal centers characteristic of cytochrome c oxidases (cytochromes a and a3; copper centers CuA and CuB) and an additional cytochrome c (Fee, J. A., Kuila, D., Mather, M. W., and Yoshida, T. (1986) Biochim. Biophys. Acta 853, 153-185). We have now cloned and sequenced the genes encoding the subunits of this enzyme. The smaller subunit consists of a typical oxidase subunit II sequence fused to a cytochrome c domain (Mather, M. W., Springer, P., and Fee, J. A. (1991) J. Biol. Chem. 266, 5025-5035). The larger subunit, the A-protein, is encoded by a fusion gene lying immediately downstream of the subunit IIc gene. The 5‘ portion of this gene encodes an oxidase subunit I homolog, whereas the 3‘ portion is homologous to oxidase subunits III. The A-protein from the purified enzyme appears too small from SDS-polyacrylamide gel electrophoresis and quantitative amino acid analyses to be a complete subunit I/III fusion, but it is currently not known if proteolytic processing occurs. Analyses of the sequences of oxidase subunits are presented which clearly identify T. thermophilus cytochrome caa3 as a bona fide member of the greater family of heme- and copper-requiring oxidases. As one consequence, it is confirmed that the set of invariant histidine residues (potential ligands of the metal centers) in cytochrome c oxidase subunits I and II is reduced to 8. Possible topological and helix packing models are developed based on considerations of homology, hydropathy, and variability.