Genetic Analysis of the Hox Hydrogenase in the Cyanobacterium Synechocystis sp PCC 6803 Reveals Subunit Roles in Association, Assembly, Maturation, and Function
Genetic Analysis of the Hox Hydrogenase in the Cyanobacterium Synechocystis sp PCC 6803 Reveals Subunit Roles in Association, Assembly, Maturation, and Function
复制标题
DOI：
10.1074/jbc.m112.392407
复制
发表时间：
2012-12-21
影响因子：
4.8
通讯作者：
Maness, Pin-Ching
中科院分区：
文献类型：
--
作者：
Eckert, Carrie;Boehm, Marko;Maness, Pin-Ching
氢酶是催化2H(+)+2E(-)H-2的金属酶。已经在包括蓝藻在内的许多细菌中发现并鉴定了一种多亚单位的双向[NiFe]-氢酶，在蓝藻中，它被认为是一个电子阀，平衡细胞中的还原剂。在蓝藻中，该HOX氢酶由两个功能部分的5个蛋白质组成：与异二聚体[NiFe]-氢酶同源的氢酶部分(HoxYH)和与呼吸复合体I的NuoEFG同源的黄递酶部分(HoxEFU)，连接NAD(P)H NAD(P)(+)作为电子的源/宿。在这里，我们提出了一个广泛的研究，在蓝藻聚球藻的HOX氢酶。PCC 6803。我们鉴定了HoxEFUYH、HoxFUYH、HoxEFU、HoxFU和HoxYH亚复合体的存在，以及未成熟、未加工的大亚基(HoxH)与其他HOX亚基和未知因素的关联，为理解HOX的成熟和组装提供了基础。对同一亲本菌株中含有单个和组合HOX基因缺失的突变体的分析表明，HoxF和HoxU在复合体/亚复合体结合中起着重要的作用。此外，对单个菌株背景中的单个和组合HOX突变表型的分析可以清楚地了解每个亚基在氢酶活性中的功能，并证明其生理功能比以前报道的更复杂，在不同的生长条件下在生长或光合作用中没有明显的外在缺陷。
Hydrogenases are metalloenzymes that catalyze 2H(+) + 2e(-) H-2. A multisubunit, bidirectional [NiFe]-hydrogenase has been identified and characterized in a number of bacteria, including cyanobacteria, where it is hypothesized to function as an electron valve, balancing reductant in the cell. In cyanobacteria, this Hox hydrogenase consists of five proteins in two functional moieties: a hydrogenase moiety (HoxYH) with homology to heterodimeric [NiFe]-hydrogenases and a diaphorase moiety (HoxEFU) with homology to NuoEFG of respiratory Complex I, linking NAD(P)H NAD(P)(+) as a source/sink for electrons. Here, we present an extensive study of Hox hydrogenase in the cyanobacterium Synechocystis sp. PCC 6803. We identify the presence of HoxEFUYH, HoxFUYH, HoxEFU, HoxFU, and HoxYH subcomplexes as well as association of the immature, unprocessed large subunit (HoxH) with other Hox subunits and unidentified factors, providing a basis for understanding Hox maturation and assembly. The analysis of mutants containing individual and combined hox gene deletions in a common parental strain reveals apparent alterations in subunit abundance and highlights an essential role for HoxF and HoxU in complex/subcomplex association. In addition, analysis of individual and combined hox mutant phenotypes in a single strain background provides a clear view of the function of each subunit in hydrogenase activity and presents evidence that its physiological function is more complicated than previously reported, with no outward defects apparent in growth or photosynthesis under various growth conditions.