Dissection of the Hydrogen Metabolism of the Enterobacterium Trabulsiella guamensis: Identification of a Formate-Dependent and Essential Formate Hydrogenlyase Complex Exhibiting Phylogenetic Similarity to Complex I
Dissection of the Hydrogen Metabolism of the Enterobacterium Trabulsiella guamensis: Identification of a Formate-Dependent and Essential Formate Hydrogenlyase Complex Exhibiting Phylogenetic Similarity to Complex I
复制标题
DOI：
10.1128/jb.00160-19
复制
发表时间：
2019-06-01
影响因子：
3.2
通讯作者：
Pinske, Constanze
中科院分区：
文献类型：
--
作者：
Lindenstrauss, Ute;Pinske, Constanze
关岛梭菌是从关岛的真空吸尘器中分离到的一种非致病性肠杆菌。它有一个H-2-氧化型HYD-2型氢酶(HYD)，编码一个放氢HYD，与未知的大肠杆菌卷曲甲酸氢解酶(FHL-2(EC))复合体最相似。关木瓜FHL-2(FHL-2(TG))复合体由5个膜整合蛋白和4~5个细胞质亚基组成。结果表明，FHL-2(TG)络合物催化甲酸盐歧化生成CO(2)和H-2。FHL-2(TG)具有与大肠杆菌FHL-1(EC)复合体类似的甲酸释放H-2的活性，但该复合体在细胞裂解时似乎更不稳定。在异源大肠杆菌宿主中克隆完整的13-kBP FHL-2(TG)操纵子，现在使我们能够明确地证明FHL-2(TG)的活性，并使我们能够用生化方法表征FHL-2(TG)复合体。虽然甲酸脱氢酶(FdhH)基因fdhF不包含在操纵子中，但FdhH是复合体的一部分，FHL-2(TG)的活性取决于大肠杆菌FdhH的存在。此外，与大肠杆菌不同的是，关岛锥虫可以发酵替代碳源纤维二糖，我们进一步研究了在这些条件下H-2氧化的HYD-2(TG)和形成H-2的FHL-2(TG)的参与。然而，为了与传统的氢气生产方法竞争，这一过程需要我们在分子水平上的理解。FHL-1(EC)复合体是高效的产氢物质，在大肠杆菌中的原型FHL-1(EC)复合体已经得到了广泛的研究。本文首次提出了一种FHL-2型复合体的生化特征。本文提供的数据将使我们能够解开长期存在的FHL-2(EC)复合体的谜团，首次对关岛锥虫的发酵代谢进行生化表征，并建立这种肠道细菌作为依赖FHL的能量守恒的模式生物。
Trabulsiella guamensis is a nonpathogenic enterobacterium that was isolated from a vacuum cleaner on the island of Guam. It has one H-2-oxidizing Hyd-2-type hydrogenase (Hyd) and encodes an H-2-evolving Hyd that is most similar to the uncharacterized Escherichia coil formate hydrogenlyase (FHL-2(Ec)) complex. The T. guamensis FHL-2 (FHL-2(Tg)) complex is predicted to have 5 membrane-integral and between 4 and 5 cytoplasmic subunits. We showed that the FHL-2(Tg) complex catalyzes the disproportionation of formate to CO(2)and H-2. FHL-2(Tg) has activity similar to that of the E. coli FHL-1(Ec) complex in H-2 evolution from formate, but the complex appears to be more labile upon cell lysis. Cloning of the entire 13-kbp FHL-2(Tg) operon in the heterologous E. coli host has now enabled us to unambiguously prove FHL-2(Tg) activity, and it allowed us to characterize the FHL-2(Tg) complex biochemically. Although the formate dehydrogenase (FdhH) gene fdhF is not contained in the operon, the FdhH is part of the complex, and FHL-2(Tg) activity was dependent on the presence of E. coli FdhH. Also, in contrast to E. coli, T. guamensis can ferment the alternative carbon source cellobiose, and we further investigated the participation of both the H-2-oxidizing Hyd-2(Tg) and the H-2-forming FHL-2(Tg) under these conditions.IMPORTANCE Biological H-2 production presents an attractive alternative for fossil fuels. However, in order to compete with conventional H-2 production methods, the process requires our understanding on a molecular level. FHL complexes are efficient H-2 producers, and the prototype FHL-1(Ec) complex in E. coli is well studied. This paper presents the first biochemical characterization of an FHL-2-type complex. The data presented here will enable us to solve the long-standing mystery of the FHL-2(Ec) complex, allow a first biochemical characterization of T. guamensis's fermentative metabolism, and establish this enterobacterium as a model organism for FHL-dependent energy conservation.