产甲烷的常温古细菌和嗜热古细菌的代谢网络比对研究

Studies on the Metabolic Network Alignment of Mesophilic and Thermophilic Methanogenic Archaea

生物网络比对是生物体的结构、功能和进化分析的重要研究手段.以从KEGG数据库获得的产甲烷的常温古细菌Methanosarcina acetivorans(M.acetivorans)和嗜热古细菌M ethanopyrus kandleri(M.kandleri)的代谢网络为对象,采用了网络比对算法M atching-based Integrative GRAph Aligner(M I-GRAAL)对它们的全局代谢网络以及hub模块网络进行了比对.比对结果表明采用度、聚集系数以及离心率三个度量参数相结合的网络比对结果明显优于其它度量参数的计算结果,且结果更稳定.同时发现常温产甲烷菌M.acetivorans的hub模块与嗜热产甲烷菌M.kandleri的hub模块相似代谢途径的拓扑基本一致,不相似的代谢网络中有81.8%以上的节点都在嗜热产甲烷菌M.kandleri的最紧密的7-核中,推测嗜热菌的耐热性可能与受到胞内酪氨酸的影响.

Biological network alignment is an important research method to the study of organism＇s structure, function and evolutionary analysis. Based on the metabolic networks of mesophilic archaea Methanosarcina acetivorans （M. acetivorans） and thermophilic archaea Methanopyrus kandleri （ M. kandleri） derived from KEGG database,this paper compares the global metabolic networks and hub modules by using a network alignment algorithm Matching-based Integrative GRAph Aligner （MI-GRAAL ）. It is found that the results are significantly better than other metrics calculations,and the results are more stable when different network metric parameters were used together,such as relative degree difference~ relative clustering coefficient difference and relative eccentricity difference. Furthermore, we find that the topological structures of the hub modules of mesophilic methanogen M. acetivorans and thermophilic methanogen M. kandleri are similar. More than 81.8% of the enzymes of their metabolic networks are in the highly closest 7-core subnetwork of thermophilic methanogen M. kandleri, which implies that the thermostability of thermophilic bacteria may be affected by the intracellular tyrosine.