Coenzyme F420-Dependent Glucose-6-Phosphate Dehydrogenase-Coupled Polyglutamylation of Coenzyme F420 in Mycobacteria.
Coenzyme F420-Dependent Glucose-6-Phosphate Dehydrogenase-Coupled Polyglutamylation of Coenzyme F420 in Mycobacteria.
复制标题
分枝杆菌中辅酶 F420 依赖的葡萄糖-6-磷酸脱氢酶偶联的辅酶 F420 多谷氨酰化。
DOI：
10.1128/jb.00375-18
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发表时间：
2018
影响因子：
3.2
通讯作者：
Mukhopadhyay,Biswarup
中科院分区：
文献类型：
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作者：
Purwantini,Endang;Loganathan,Usha;Mukhopadhyay,Biswarup
辅酶F420在包括结核分枝杆菌在内的各种古生菌和细菌的氧化还原代谢中起着关键作用。在结核分枝杆菌中，依赖于F420的反应与几个毒力因子有关。F420在侧链上携带多个谷氨酸残基，形成F420-n物种(n，谷氨酸残基数量)，该侧链的长度影响细胞生理。具有较短侧链的结核分枝杆菌F420菌株对两种新的结核病药物delamanid和pretomanid表现出耐药性。因此，F420的多谷氨酰化过程引起了人们的极大兴趣。遗传分析表明，在分枝杆菌中，F420-0γ-谷氨酰连接酶(FbiB)将多达7个谷氨酸残基引入F420。然而，纯化的结核分枝杆菌FbiB(MtbFbiB)要么效率低下，要么不能结合两种以上的谷氨酸。我们发现，在体外，如果F420以两电子还原状态(F420H2)呈现给酶，MtbFbiB会合成含有多达7个谷氨酸残基的侧链。我们对牛分枝杆菌、卡介苗和耻垢分枝杆菌的遗传分析以及对结核分枝杆菌的文献数据分析表明，在这些分枝杆菌中，多聚谷氨酰化过程需要F420依赖的葡萄糖-6-磷酸脱氢酶(FGD)的协助，F420将F420还原为F420H2。我们假设，从F420-0H2开始，FbiB的氨基末端结构域构建F420-2H2，然后F420-2H2被转移到羧基末端结构域进行进一步的谷氨酰化；F420-2H2在结构上修饰羧基末端结构域以适应更长的谷氨酸链。这个系统类似于叶基多谷氨酸合成酶，只有在维生素还原为四氢叶酸后，才会在叶酸中引入不止一个谷氨酸残基。重要的是，结核分枝杆菌辅酶F420依赖于导致结核病的反应，可能导致这种细菌的毒力。辅酶携带一条谷氨酸衍生的尾巴，其长度影响结核分枝杆菌的新陈代谢。消除带有更长尾巴的F420产生的突变使结核分枝杆菌对两种新的结核病药物产生抗药性。本报告描述了F420较长的谷氨酰尾的合成需要两种酶的协同作用，其中一种酶在另一种酶的作用之前还原辅酶，另一种酶催化多谷氨酰化。这些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B9)的侧链需要类似的协同作用，其中一个酶将维生素还原为四氢叶酸，另一个酶催化多谷氨酸化；叶酸是DNA和氨基酸合成所必需的。因此，报道的研究还揭示了两个重要的细胞系统之间的关键相似之处。
Coenzyme F420plays a key role in the redox metabolisms of various archaea and bacteria, including Mycobacterium tuberculosis. In M. tuberculosis, F420-dependent reactions have been linked to several virulence factors. F420carries multiple glutamate residues in the side chain, forming F420-nspecies (n, number of glutamate residues), and the length of this side chain impacts cellular physiology. M. tuberculosis strains with F420species carrying shorter side chains exhibit resistance to delamanid and pretomanid, two new tuberculosis (TB) drugs. Thus, the process of polyglutamylation of F420is of great interest. It has been known from genetic analysis that in mycobacteria an F420-0 γ-glutamyl ligase (FbiB) introduces up to seven glutamate residues into F420. However, purified FbiB of M. tuberculosis (MtbFbiB) is either inefficient or incapable of incorporating more than two glutamates. We found that,in vitro,MtbFbiB synthesized side chains containing up to seven glutamate residues if F420was presented to the enzyme in a two-electron reduced state (F420H2). Our genetic analysis in Mycobacterium bovis BCG and Mycobacterium smegmatis and an analysis of literature data on M. tuberculosis revealed that in these mycobacteria the polyglutamylation process requires the assistance of F420-dependent glucose-6-phosphate dehydrogenase (Fgd) which reduces F420to F420H2. We hypothesize that, starting with F420-0H2, the amino-terminal domain of FbiB builds F420-2H2, which is then transferred to the carboxy-terminal domain for further glutamylation; F420-2H2modifies 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.IMPORTANCECoenzyme F420-dependent reactions of Mycobacterium tuberculosis, 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 M. tuberculosis. Mutations that eliminate the production of F420with longer tails make M. tuberculosis resistant to two new tuberculosis drugs. This report describes that the synthesis of longer glutamyl tails of F420requires 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 B9) 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.