A methylaspartate cycle in haloarchaea.
Access to novel ecological niches often requires adaptation of metabolic pathways to cope with new environments. For conversion to cellular building blocks, many substrates enter central carbon metabolism via acetyl-coenzyme A (acetyl-CoA). Until now, only two such pathways have been identified: the glyoxylate cycle and the ethylmalonyl-CoA pathway. Prokaryotes in the haloarchaea use a third pathway by which acetyl-CoA is oxidized to glyoxylate via the key intermediate methylaspartate. Glyoxylate condensation with another acetyl-CoA molecule yields malate, the final assimilation product. This cycle combines reactions that originally belonged to different metabolic processes in different groups of prokaryotes, which suggests lateral gene transfer and evolutionary tinkering of acetate assimilation. Moreover, it requires elevated intracellular glutamate concentrations, as well as coupling carbon assimilation with nitrogen metabolism.
Mikrobiologie, Fakultät Biologie, Universität Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany.
Maria
M
Khomyakova
Özlem
Ö
Bükmez
Lorenz K
LK
Thomas
Tobias J
TJ
Erb
Ivan A
IA
Berg
D000085:Acetates / Q000378:metabolism*; D000105:Acetyl Coenzyme A / Q000378:metabolism; D019843:Archaeal Proteins / Q000378:metabolism; D005650:Fumarates / Q000378:metabolism; D022761:Gene Transfer, Horizontal; D019766:Genes, Archaeal; D018698:Glutamic Acid / Q000378:metabolism; D006038:Glyoxylates / Q000378:metabolism; D019614:Haloarcula marismortui / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D008293:Malates / Q000378:metabolism; D008298:Maleates / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D016202:N-Methylaspartate / Q000378:metabolism*; D010084:Oxidation-Reduction; D020543:Proteome; D019802:Succinic Acid / Q000378:metabolism
D000085:Acetates; D019843:Archaeal Proteins; D005650:Fumarates; D006038:Glyoxylates; D008293:Malates; D008298:Maleates; D020543:Proteome; C073341:citraconic acid; D018698:Glutamic Acid; D016202:N-Methylaspartate; D000105:Acetyl Coenzyme A; C030298:malic acid; D019802:Succinic Acid