产甲烷
格式化
甲烷球菌
甲酸脱氢酶
黄素单核苷酸
黄素组
甲烷杆菌
化学
氢化酶
生物化学
辅因子
立体化学
生物
酶
甲烷
基因
古细菌
催化作用
有机化学
作者
Mohd Farid Abdul Halim,Dallas R. Fonseca,Thomas D. Niehaus,Kyle C. Costa
标识
DOI:10.1101/2023.05.09.540023
摘要
Abstract Methanogens are essential for the complete remineralization of organic matter in anoxic environments. Most cultured methanogens are hydrogenotrophic, using H 2 as an electron donor to reduce CO 2 to CH 4 , but in the absence of H 2 many can also use formate. Formate dehydrogenase (Fdh) is essential for formate oxidation, where it transfers electrons for reduction of coenzyme F 420 or to a flavin-based electron bifurcating reaction catalyzed by heterodisulfide reductase (Hdr), the terminal reaction of methanogenesis. How these competing reactions are coordinated is unknown. Furthermore, methanogens that use formate encode at least two isoforms of Fdh in their genomes, but how these different isoforms participate in methanogenesis is also unknown. Using Methanococcus maripaludis , we undertook a biochemical characterization of both Fdh isoforms involved in methanogenesis. Both Fdh1 and Fdh2 interacted with Hdr to catalyze the flavin-based electron bifurcating reaction, and both reduced F 420 at similar rates. F 420 reduction preceded flavin-based electron bifurcation activity for both enzymes. In a Δ fdh1 mutant background, a suppressor mutation was required for Fdh2 activity. Genome sequencing revealed that this mutation resulted in loss of a specific molybdopterin transferase ( moeA ), allowing for Fdh2-dependent growth. This suggests that both isoforms of Fdh are functionally redundant, but their activities in vivo may be limited by gene regulation under different growth conditions. Together these results expand our understanding of formate oxidation and the role of Fdh in methanogenesis.
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