title: Glucose catabolism in two derivatives of a Rhizobium japonicum strain differing in nitrogen-fixing efficiency.
abstract: Radiorespirometric and enzymatic analyses reveal that glucose-grown cells of Rhizobium japonicum isolates I-110 and L1-110, both derivatives of R. japonicum strain 3I1b110, possess an active tricarboxylic acid cycle and metabolize glucose by simultaneous operation of the Embden-Meyerhof-Parnas and Entner-Doudoroff pathways. The hexose cycle may play a minor role in the dissimilation of glucose. Failure to detect the nicotinamide adenine dinucleotide phosphate-dependent decarboxylating 6-phosphogluconate dehydrogenase (EC 1.1.1.44) evidences absence of the pentose phosphate pathway. Transketolase and transaldolase reactions, however, enable R. japonicum to produce the precursors for purine and pyrimidine biosynthesis from fructose-6-phosphate and glyceraldehyde-3-phosphate. A constitutive nicotinamide adenine dinucleotide-linked 6-phosphogluconate dehydrogenase has been detected. The enzyme is stimulated by either mannitol or fuctose and might initiate a new catabolic pathway. R. japonicum isolate I-110, characterized by shorter generation times on glucose and greater nitrogen-fixing efficiency, oxidizes glucose more extensively than type L1-110 and utilizes preferentially the Embden-Meyerhof-Parnas pathway, whereas the Entner-Doudoroff pathway apparently predominates in type L1-110.
mesh_terms: D002237:Carbohydrate Dehydrogenases / Q000378:metabolism; D002952:Citric Acid Cycle; D005947:Glucose / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D009586:Nitrogen Fixation; D010428:Pentosephosphates / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D012231:Rhizobium / Q000201:enzymology / Q000378:metabolism*; D013045:Species Specificity; D014153:Transaldolase / Q000378:metabolism; D014174:Transketolase / Q000378:metabolism
chemical_list: D010428:Pentosephosphates; D011773:Pyruvates; D002237:Carbohydrate Dehydrogenases; D005954:Glucosephosphate Dehydrogenase; D014174:Transketolase; D014153:Transaldolase; D005947:Glucose