Examination of the Glycine Betaine-Dependent Methylotrophic Methanogenesis Pathway: Insights Into Anaerobic Quaternary Amine Methylotrophy
Examination of the Glycine Betaine-Dependent Methylotrophic Methanogenesis Pathway: Insights Into Anaerobic Quaternary Amine Methylotrophy
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DOI：
10.3389/fmicb.2019.02572
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发表时间：
2019-11-07
影响因子：
5.2
通讯作者：
Ferguson, Donald J., Jr.
中科院分区：
文献类型：
--
作者：
Creighbaum, Adam J.;Ticak, Tomislav;Ferguson, Donald J., Jr.
最近的研究表明，环境中丰富的季胺（QAs）是产甲烷的主要来源，但分解代谢酶是未知的。我们假设，产甲烷古菌Methanolobus vulcani B1d代谢甘氨酸甜菜碱（GB）通过一个corrinoid依赖的GB：辅酶M（CoM）甲基转移途径。对M. vulcani B1d揭示了编码预测的非吡咯赖氨酸MttB同源物（MV8460）的基因，其与由Desulfitobacterium cuberniense Y51编码的GB甲基转移酶具有高序列相似性。MV8460催化游离cob（I）丙氨酸的GB依赖性甲基化，表明其是真实的MtgB酶。蛋白质组学分析表明，MV8460和一个corrinoid结合蛋白（MV8465）在M. vulcani B1d在GB上生长相对于在三甲胺上生长。类咕啉还原活化酶（MV10335）和甲基类咕啉：CoM甲基转移酶（MV10360）的丰度显着高于GB生长的B1d裂解物相比，其他同系物。使用重组MV8460、MV8465、MV10335和MV10360在体外完全重建GB：CoM途径。完整GB：CoM途径的证明扩展了直接QA依赖性甲基营养的知识，并建立了一个模型，以确定其他生态相关的厌氧季胺途径。
Recent studies indicate that environmentally abundant quaternary amines (QAs) are a primary source for methanogenesis, yet the catabolic enzymes are unknown. We hypothesized that the methanogenic archaeon Methanolobus vulcani B1d metabolizes glycine betaine (GB) through a corrinoid-dependent GB:coenzyme M (CoM) methyl transfer pathway. The draft genome sequence of M. vulcani B1d revealed a gene encoding a predicted non-pyrrolysine MttB homolog (MV8460) with high sequence similarity to the GB methyltransferase encoded by Desulfitobacterium hafniense Y51. MV8460 catalyzes GB-dependent methylation of free cob(I)alamin indicating it is an authentic MtgB enzyme. Proteomic analysis revealed that MV8460 and a corrinoid binding protein (MV8465) were highly abundant when M. vulcani B1d was grown on GB relative to growth on trimethylamine. The abundance of a corrinoid reductive activation enzyme (MV10335) and a methylcorrinoid:CoM methyltransferase (MV10360) were significantly higher in GB-grown B1d lysates compared to other homologs. The GB:CoM pathway was fully reconstituted in vitro using recombinant MV8460, MV8465, MV10335, and MV10360. Demonstration of the complete GB:CoM pathway expands the knowledge of direct QA-dependent methylotrophy and establishes a model to identify additional ecologically relevant anaerobic quaternary amine pathways.