Carbamate kinase can replace in vivo carbamoyl phosphate synthetase. Implications for the evolution of carbamoyl phosphate biosynthesis

The exclusive involvement of carbamate kinase (CK) in fermentative ATP prod uction and of carbamoyl phosphate synthetase (CPS) in the production of car bamoyl phosphate (CP) for pyrimidines and arginine biosynthesis was challen ged by the finding of CK as the only activity synthesising CP in the archae a Pyrococcus furiosus and Pyrococcus abyssi. We now show that CK can replac e CPS in vivo: transformation of Escherichia coli devoid of the CPS gene wi th plasmids encoding the CK from P. furiosus or from Enterococcas faecalis (which uses CK for making ATP) restores the ability of CPS-deficient E, col i to grow in the absence of arginine and uracil if ammonia and bicarbonate are present. (C) 2000 Federation of European Biochemical Societies. Publish ed by Elsevier Science B.V. All rights reserved.