A 12-cistron Escherichia coli operon (hyf) encoding a putative proton-translocating formate hydrogenlyase system
A 12-cistron Escherichia coli operon (hyf) encoding a putative proton-translocating formate hydrogenlyase system
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DOI：
10.1099/00221287-143-11-3633
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发表时间：
1997-11-01
期刊：
影响因子：
2.8
通讯作者：
Guest, JR
中科院分区：
文献类型：
--
作者：
Andrews, SC;Berks, BC;Guest, JR
大肠杆菌的12个基因操纵子(hyf操纵子，hyfABCDEFGHIR-FocB)的核苷酸序列已经确定。Hyf操纵子位于55.8-56.0min，编码一个可能的九亚单位氢酶复合体(氢酶4或Hyf)，一个潜在的依赖于甲酸和Sigma(54)的转录激活因子HYFR(与FhlA相关)，以及一个可能的甲酸转运蛋白FocB(与FocA相关)。9个Hyf复合体中有5个亚基既与大肠杆菌氢酶-3复合体(HYC)有关，又与质子转运NADH：苯醌氧化还原酶(复合体I和Nuo)的亚基有关，而2个Hyf亚基仅与NADH：苯醌氧化还原酶亚基有关。Hyf组分包括一个预测的523个残基[Ni-Fe]氢酶(大亚基)，N端(残基1-170)与络合物I的30 kDa或nuoc亚基同源。我们认为Hyf与甲酸脱氢酶H(FDH-H)一起形成了一个迄今未被识别的呼吸作用相关的质子转移甲酸氢解酶(FHL-2)。HYFR可能作为HYF操纵子的甲酸盐依赖的调节子，FocB为HYF复合体提供外部甲酸盐作为底物。
The nucleotide sequence has been determined for a twelve-gene operon of Escherichia coli designated the hyf operon (hyfABCDEFGHIR-focB). The hyf operon is located at 55.8-56.0 min and encodes a putative nine-subunit hydrogenase complex (hydrogenase four or Hyf), a potential formate-and sigma(54)-dependent transcriptional activator, HyfR (related to FhlA), and a possible formate transporter, FocB (related to FocA). Five of the nine Hyf-complex subunits are related to subunits of both the E. coli hydrogenase-3 complex (Hyc) and the proton-translocating NADH:quinone oxidoreductases (complex I and Nuo), whereas two Hyf subunits are related solely to NADH:quinone oxidoreductase subunits. The Hyf components include a predicted 523 residue [Ni-Fe] hydrogenase (large subunit) with an N-terminus (residues 1-170) homologous to the 30 kDa or NuoC subunit of complex I. It is proposed that Hyf, in conjunction with formate dehydrogenase H (Fdh-H), forms a hitherto unrecognized respiration-linked proton-translocating formate hydrogenlyase (FHL-2). It is likely that HyfR acts as a formate-dependent regulator of the hyf operon and that FocB provides the Hyf complex with external formate as substrate.