Metabolism of D-mannose in Aerobacter aerogenes: evidence for a cyclic pathway.

Kamel, M. Y. (Michigan State University, East Lansing), and R. L. Anderson. Metabolism of d-mannose in Aerobacter aerogenes: evidence for a cyclic pathway. J. Bacteriol. 92:1689-1697. 1966.-Evidence is presented which suggests a cyclic pathway for the constitutive utilization of d-mannose in extracts of Aerobacter aerogenes PRL-R3. d-Mannose is phosphorylated with d-glucose-6-phosphate to yield d-mannose-6-phosphate and d-glucose. d-Glucose-6-phosphate may be regenerated by isomerization of d-mannose-6-phosphate through d-fructose-6-phosphate, or by phosphorylation of d-glucose with adenosine-5'-triphosphate. The pathway involves the participation of four constitutive enzymes: d-glucose-6-phosphate isomerase, d-mannose-6-phosphate isomerase, a stereospecific d-glucokinase, and a phosphotransferase which phosphorylates d-mannose with d-glucose-6-phosphate, acetyl phosphate, or carbamyl phosphate. The absence of d-mannokinase (adenosine-5'-triphosphate:d-mannose phosphotransferase) activity in extracts of this organism suggests that the pathway may be of functional significance. Also, the pathway accounts for an apparent 2-epimerization of d-mannose to d-glucose that was observed in extracts.