Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA.
J Bacteriol. 2018 Nov 6;200(23). doi: 10.1128/JB.00375-18. Print 2018 Dec 1.
Coenzyme F plays a key role in the redox metabolisms of various archaea and bacteria, including In , F-dependent reactions have been linked to several virulence factors. F carries multiple glutamate residues in the side chain, forming F- species (, number of glutamate residues), and the length of this side chain impacts cellular physiology. strains with F species carrying shorter side chains exhibit resistance to delamanid and pretomanid, two new tuberculosis (TB) drugs. Thus, the process of polyglutamylation of F is of great interest. It has been known from genetic analysis that in mycobacteria an F-0 γ-glutamyl ligase (FbiB) introduces up to seven glutamate residues into F However, purified FbiB of (FbiB) is either inefficient or incapable of incorporating more than two glutamates. We found that, , FbiB synthesized side chains containing up to seven glutamate residues if F was presented to the enzyme in a two-electron reduced state (FH). Our genetic analysis in BCG and and an analysis of literature data on revealed that in these mycobacteria the polyglutamylation process requires the assistance of F-dependent glucose-6-phosphate dehydrogenase (Fgd) which reduces F to FH We hypothesize that, starting with F-0H, the amino-terminal domain of FbiB builds F-2H, which is then transferred to the carboxy-terminal domain for further glutamylation; F-2H modifies the carboxy-terminal domain structurally to accommodate longer glutamyl chains. This system is analogous to folylpolyglutamate synthase, which introduces more than one glutamate residue into folate only after this vitamin is reduced to tetrahydrofolate. Coenzyme F-dependent reactions of , which causes tuberculosis, potentially contributes to the virulence of this bacterium. The coenzyme carries a glutamic acid-derived tail, the length of which influences the metabolism of Mutations that eliminate the production of F with longer tails make resistant to two new tuberculosis drugs. This report describes that the synthesis of longer glutamyl tails of F requires concerted actions of two enzymes, one of which reduces the coenzyme prior to the action of the other, which catalyzes polyglutamylation. This knowledge will help to develop more effective tuberculosis (TB) drugs. Remarkably, the introduction of multiple glutamate residues into the sidechain of folate (vitamin B) requires similar concerted actions, where one enzyme reduces the vitamin to tetrahydrofolate and the other catalyzes polyglutamylation; folate is required for DNA and amino acid synthesis. Thus, the reported research has also revealed a key similarity between two important cellular systems.
辅酶 F 在各种古菌和细菌的氧化还原代谢中发挥着关键作用，包括 。F 依赖性反应与几种毒力因子有关。F 在侧链中携带多个谷氨酸残基，形成 F- 物种（ ，谷氨酸残基数），侧链的长度会影响细胞生理学。F 物种携带较短侧链的 菌株对两种新的结核病（TB）药物——德拉马尼德和普托马尼德具有抗性。因此，F 的多聚谷氨酸化过程非常重要。从遗传分析可知，在分枝杆菌中，一种 F-0 γ-谷氨酰连接酶（FbiB）将多达七个谷氨酸残基引入 F 中。然而，纯化的 FbiB（FbiB）要么效率低下，要么无法掺入超过两个谷氨酸。我们发现，如果 F 以两个电子还原态（FH）呈现给酶， ，FbiB 可以合成含有多达七个谷氨酸残基的侧链。我们在 BCG 和 和对 的文献数据的分析表明，在这些分枝杆菌中，多聚谷氨酸化过程需要 F 依赖性葡萄糖-6-磷酸脱氢酶（Fgd）的辅助，该酶将 F 还原为 FH 我们假设，从 F-0H 开始，FbiB 的氨基末端结构域构建 F-2H，然后将其转移到羧基末端结构域进行进一步的谷氨酸化；F-2H 从结构上修饰羧基末端结构域以容纳更长的谷氨酰链。该系统类似于叶酸多聚谷氨酸合酶，该酶仅在维生素还原为四氢叶酸后才将一个以上的谷氨酸残基引入叶酸。依赖辅酶 F 的反应，这会导致结核病，可能有助于这种细菌的毒力。辅酶携带一个谷氨酸衍生的尾巴，其长度会影响 的代谢。消除较长尾部的 F 产生的突变使 对两种新的结核病药物具有抗性。本报告描述了 F 更长谷氨酰侧链的合成需要两种酶的协同作用，其中一种酶在另一种酶催化多聚谷氨酸化之前还原辅酶。这一知识将有助于开发更有效的结核病（TB）药物。值得注意的是，将多个谷氨酸残基引入叶酸（维生素 B）的侧链需要类似的协同作用，其中一种酶将维生素还原为四氢叶酸，另一种酶催化多聚谷氨酸化；叶酸是 DNA 和氨基酸合成所必需的。因此，该报告的研究还揭示了两个重要细胞系统之间的一个关键相似性。
