The role of uncharacterized methyl-x:coenzyme M methyltransferases for activation of novel methylotrophic energy substrates in Methanosarcina acetivorans

产甲烷古菌负责大部分生物产生的甲烷。这个过程，甲烷生成，在碳循环，全球变暖，替代能源战略，废物处理和农业中发挥着关键作用。甲烷八叠球菌属物种具有非常广泛的底物谱，并且能够利用H2+CO2、一氧化碳、乙酸盐和甲基化化合物来节约能量。在后一种称为甲基营养型产甲烷的过程中，甲基化化合物通过底物特异性甲基转移酶的活化进入产甲烷途径，甲基转移酶将甲基转移到辅酶M（CoM）。模型产甲烷八叠球菌醋酸甲烷的基因组编码几个未知的甲基-x：辅酶M甲基转移酶（xMT）贷款的假设，生物体的甲基营养能力超过已知的。在测试的许多潜在底物中，一些甲氧基化化合物支持生长并通过甲醇特异性途径代谢，这使得关于xMT的作用的问题仍然是开放的。在第二个资助期内，将分析这些化合物和其他含甲基化合物的共代谢，以评估xMT的作用，底物周转的潜在环境相关性，以及甲醇，甲胺和甲基硫化物的甲基转移酶系统的底物范围。此外，二甲基硫醚活化的生化分析-低至原子水平-将提供对环境重要的挥发性硫物质代谢的详细见解。甲烷八叠球菌编码的许多甲基转移酶是其似是而非的遗传冗余的典范，并承诺对这些重要生物体的代谢多样性的新见解。

Methanogenic archaea are responsible for most of the biologically produced methane. This process, methanogenesis, plays a critical role in the carbon cycle, global warming, alternative energy strategies, waste treatment and agriculture. Methanosarcina species have a comparably broad substrate spectrum and are able to utilize H2+CO2, carbon monoxide, acetate, and methylated compounds for energy conservation. During the latter, called methylotrophic methanogenesis, methylated compounds enter the methanogenic pathway via activation by substrate-specific methyltransferases, which transfer the methyl group to coenzyme M (CoM). The genome of the model methanogen Methanosarcina acetivorans encodes several uncharacterized methyl-x:coenzyme M methyltransferases (xMTs) lending to the hypothesis that the organism’s methylotrophic capacity exceeds the known one. Of numerous potential substrates tested some methoxylated compounds supported growth and were metabolized via the methanol-specific pathway, which leaves the question as to the role of the xMTs still open. In the second grant period, co-metabolism of those and other methyl-containing compounds will be analyzed to assess the role of the xMTs, the potential environmental relevance of substrate turnover, and the substrate range of the methyltransferase systems for methanol, methylamines and methylsulfides. Furthermore, biochemical analysis of dimethylsulfide activation -down to the atomic level- will provide detailed insights in the metabolism of environmentally important volatile sulfur species. The many methyltransferases encoded in Methanosarcina are paradigmatic for their specious genetic redundancy and promise novel insights into the metabolic versatility of these important organisms.