Genome scale metabolic modeling reveals the metabolic potential of three Type II methanotrophs of the genus Methylocystis
Genome scale metabolic modeling reveals the metabolic potential of three Type II methanotrophs of the genus Methylocystis
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DOI：
10.1016/j.ymben.2019.04.001
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发表时间：
2019-07-01
影响因子：
8.4
通讯作者：
Munoz, Raul
中科院分区：
文献类型：
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作者：
Bordel, Sergio;Rodriguez, Yadira;Munoz, Raul
最近测序的粗毛甲壳藻和其他两种甲氧菌的基因组规模代谢模型(GSMM)已经被重建。这些生物是第二类甲烷营养细菌，能够在营养限制的条件下积累多羟基烷酸。第一次，GSMM被重建为II型甲烷氧化菌。这些模型结合粗毛甲藻的实验生物量和PHB产量，可以阐明这些生物体中甲烷被颗粒甲烷单加氧酶(PMMO)氧化的机理。与使用“直接耦合机制”的I型甲烷氧化菌不同，II型甲烷氧化菌似乎使用所谓的“氧化还原臂机制”。通过邻苯二酚对络合物I的抑制，证实了氧化还原臂机制的应用，即甲烷氧化与呼吸链的络合物I之间的偶联。与第一类甲烷氧化菌相比，利用“氧化还原臂”机制，甲烷的生物量产量较低。然而，在氮素限制条件下，II型甲烷氧化菌能够将高代谢碳流重新定向到乙酰乙酰-辅酶A，这使得这些生物成为代谢工程的良好平台。
Genome Scale Metabolic Models (GSMMs) of the recently sequenced Methylocystis hirsuta and two other methanotrophs from the genus Methylocystis have been reconstructed. These organisms are Type II methanotrophs with the ability of accumulating Polyhydroxyalkanoates under nutrient limiting conditions. For the first time, GSMMs have been reconstructed for Type II methanotrophs. These models, combined with experimental biomass and PHB yields of Methylocystis hirsuta, allowed elucidating the methane oxidation mechanism by the enzyme pMMO (particulate methane monooxygenase) in these organisms. In contrast to Type I methanotrophs, which use the "direct coupling mechanism", Type II methanotrophs appear to use the so called "redox arm mechanism". The utilization of the "redox arm mechanism", which involves the coupling between methane oxidation and complex I of the respiratory chain, was confirmed by inhibition of complex I with catechol. Utilization of the "redox arm" mechanism leads to lower biomass yields on methane compared to Type I methanotrophs. However, the ability of Type II methanotrophs to redirect high metabolic carbon fluxes towards acetoacetyl-CoA under nitrogen limiting conditions makes these organisms promising platforms for metabolic engineering.