title: Analysis of the intermediary metabolism of a reductive chemoautotroph.
abstract: All extant life forms depend, directly or indirectly, on the autotrophic fixation of the dominant elements of the biosphere: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. We have earlier presented the canonical network of reactions that constitute the anabolism of a reductive chemoautotroph. Separating this network into subgraphs reveals several empirical generalizations: (1) acetate (acetyl-CoA), pyruvate, phosphoenol pyruvate, oxaloacetate, and 2-oxoglutarate serve as universal starting points for all pathways leading to the universal building blocks-20 amino acids and 4 ribonucleotide triphosphates; (2) all pathways are anabolic; (3) all reactions operate by complete utilization of outputs with no molecules left behind as waste, ensuring conservation of information; (4) the core metabolome of 120 compounds is acidic, consisting of compounds containing phosphoric or carboxylic acid or both; and (5) the core network is both brittle-vulnerable to a single break-and robust-having persisted for 4 billion years. Preliminary analysis of the chemical reactions and resultant structures reveals (a) a sparseness among possible molecular structures; (b) subdomains in the network; and (c) restriction of anabolism to a small set of rudimentary organic reactions with limited diversity in chemical mechanisms. These generalizations have implications for biogenesis and trophic ecology.
authors.affiliation: Krasnow Institute for Advanced Studies, George Mason University, Fairfax, Virginia 22030, USA. vsriniva@gmu.edu
authors.forename: Vijayasarathy
authors.initials: V
authors.lastname: Srinivasan
authors.forename: Harold J
authors.initials: HJ
authors.lastname: Morowitz
mesh_terms: D000596:Amino Acids / Q000096:biosynthesis; D052818:Autotrophic Processes; D053898:Biosynthetic Pathways; D002244:Carbon / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D055432:Metabolomics; D009584:Nitrogen / Q000378:metabolism*; D009711:Nucleotides / Q000096:biosynthesis; D010100:Oxygen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D009711:Nucleotides; D010758:Phosphorus; D013455:Sulfur; D002244:Carbon; D006859:Hydrogen; D009584:Nitrogen; D010100:Oxygen