title: A 3-hydroxypropionate/4-hydroxybutyrate autotrophic carbon dioxide assimilation pathway in Archaea.
abstract: The assimilation of carbon dioxide (CO2) into organic material is quantitatively the most important biosynthetic process. We discovered that an autotrophic member of the archaeal order Sulfolobales, Metallosphaera sedula, fixed CO2 with acetyl-coenzyme A (acetyl-CoA)/propionyl-CoA carboxylase as the key carboxylating enzyme. In this system, one acetyl-CoA and two bicarbonate molecules were reductively converted via 3-hydroxypropionate to succinyl-CoA. This intermediate was reduced to 4-hydroxybutyrate and converted into two acetyl-CoA molecules via 4-hydroxybutyryl-CoA dehydratase. The key genes of this pathway were found not only in Metallosphaera but also in Sulfolobus, Archaeoglobus, and Cenarchaeum species. Moreover, the Global Ocean Sampling database contains half as many 4-hydroxybutyryl-CoA dehydratase sequences as compared with those found for another key photosynthetic CO2-fixing enzyme, ribulose-1,5-bisphosphate carboxylase-oxygenase. This indicates the importance of this enzyme in global carbon cycling.
authors: Mikrobiologie, Fakultät Biologie, Universität Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany.
authors: Ivan A
authors: IA
authors: Berg
authors: Daniel
authors: D
authors: Kockelkorn
authors: Wolfgang
authors: W
authors: Buckel
authors: Georg
authors: G
authors: Fuchs
mesh_terms: D000105:Acetyl Coenzyme A / Q000378:metabolism; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D000214:Acyl Coenzyme A / Q000378:metabolism; D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001105:Archaea / Q000235:genetics / Q000378:metabolism; D052818:Autotrophic Processes; D001639:Bicarbonates / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D019766:Genes, Archaeal; D006836:Hydro-Lyases / Q000235:genetics / Q000378:metabolism; D006885:Hydroxybutyrates / Q000378:metabolism*; D007700:Kinetics; D019344:Lactic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010788:Photosynthesis; D010802:Phylogeny; D016943:Sulfolobaceae / Q000235:genetics / Q000378:metabolism*
chemical_list: D000214:Acyl Coenzyme A; D001639:Bicarbonates; D006885:Hydroxybutyrates; D002245:Carbon Dioxide; C111420:4-hydroxybutyric acid; D019344:Lactic Acid; D000105:Acetyl Coenzyme A; C012046:succinyl-coenzyme A; C031601:hydracrylic acid; C066370:4-hydroxybutyryl-CoA dehydratase; D006836:Hydro-Lyases; D000103:Acetyl-CoA Carboxylase