The H2-sensing complex of Ralstonia eutropha:: interaction between a regulatory [NiFe] hydrogenase and a histidine protein kinase
The H2-sensing complex of Ralstonia eutropha:: interaction between a regulatory [NiFe] hydrogenase and a histidine protein kinase
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DOI：
10.1111/j.1365-2958.2003.03933.x
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发表时间：
2004-03-01
影响因子：
3.6
通讯作者：
Friedrich, B
中科院分区：
文献类型：
--
作者：
Buhrke, T;Lenz, O;Friedrich, B
两个[NiFe]氢酶使蛋白细菌Ralstonia eutroa H16能够以分子氢为唯一能源生长。第三个[NiFe]氢酶(RH)在控制氢酶基因转录的多组分信号转导链中扮演H-2传感器的角色。RH形成二聚异二聚体(HoxBC)(2)，其中HoxC含有H-2敏感活性部位，HoxB含有电子转移组分，包括一种有机的、尚未鉴定的氧化还原辅因子。这种寡聚体与组氨酸蛋白激酶HoxJ形成紧密的复合体。传感器和激酶都通过突变分析了在H-2信号传递中起重要作用的功能区。HoxB中一个55个氨基酸的C端肽的缺失突变体失去了H-2敏感能力，但仍催化H-2氧化。突变蛋白不能与HoxJ形成二聚异二聚体和复合体。在被截断的传感器中不再检测到有机氧化还原辅因子。HoxJ的PAS结构域的缺失也取消了H-2感觉，表明该结构域参与了信号转导。HoxJ的截短版本仍然能够与RH形成复合体，而HoxJ只包含该激酶的输入域。对纯化的HoxJ蛋白进行质量检测，结果表明该蛋白形成同源四聚体。讨论了H-2敏感复合体的独特低聚结构及其调节功能。
Two [NiFe] hydrogenases enable the proteobacterium Ralstonia eutropha H16 to grow on molecular hydrogen as the sole energy source. A third [NiFe] hydrogenase (RH) acts as an H-2 sensor in a multiple component signal transduction chain that controls hydrogenase gene transcription. The RH forms a dimeric heterodimer (HoxBC)(2) in which HoxC contains the H-2-sensing active site and HoxB the electron-transferring components including an organic, not yet identified redox cofactor. This oligomer forms a tight complex with the histidine protein kinase HoxJ. Both the sensor and the kinase were analysed by mutagenesis for functional domains that are instrumental in H-2 signal transmission. A mutant deleted for a C-terminal peptide of 55 amino acids in HoxB lost its H-2-sensing ability but still catalysed H-2 oxidation. The mutant protein failed to form the dimeric heterodimer and a complex with HoxJ. The organic redox cofactor was no longer detectable in the truncated sensor. H-2 sensing was also abolished by deletion of the PAS domain of HoxJ, indicating that this domain is involved in signal transduction. A truncated version of HoxJ consisting of only the input domain of the kinase was still capable of forming a complex with the RH. Mass determination of the purified HoxJ protein revealed that the kinase forms a homotetramer. The unique oligomeric structure of the H-2-sensing complex with respect to its regulatory function is discussed.