The Canonical Network of Autotrophic Intermediary Metabolism: Minimal Metabolome of a Reductive Chemoautotroph

摘要

Chemoautorophs that fix carbon by the reduc-tive tricarboxylic acid cycle represent one of the dominantbacterial life forms that make a major contribution to bio-mass production. From the viewpoint of biogenesis, con-struction of a canonical chart of intermediary metabolismfor this class of organisms may help us to understand earlycellular evolution and point us to the last universal commonancestor. Data-mining the KEGG Pathways database en--abled us to integrate required biosynthetic pathways andderive a chart that represents the complete anabolic networkof a reductive chemoautotroph. Compounds of this meta-bolic network together constitute a representative minimalmetabolome that comprises 287 metabolites. These com-pounds have been classified into different groups includingthose compounds that form nodes in the network. It can beseen that a relatively sparse set of organic chemical reac-tions dominate the anabolic synthesis in the assembly of theminimal autotrophic metabolome. Empirical generalizationsthat result from analyzing this metabolic network may aid inelucidating selection rules that govern its emergence andfurther evolution and may also help in delineating attributesthat impart the observed robustness to these metabolites.