Metabolism of L-rhamnose in Arthrobacter Pyridinolis

J Gen Microbiol. 1976 Aug;96(2):277-86. doi: 10.1099/00221287-95-2-277.

Abstract

In Arthrobacter pyridinolis, a respiration-coupled transport system for L-rhamnose caused accumulation of free L-rhamnose, while a phosphoenolpyruvate: L-rhamnose phosphotransferase system caused accumulation of L-rhamnose I-phosphate (Levinson & Krulwich, 1974). The pathways for subsequent metabolism of L-rhamnose and L-rhamose I-phosphate have now been investigated. Arthrobacter pyridinolis contains an inducible L-rhamnose isomerase and L-rhamnulokinase, as well as a constitutive L-rhamnulose I-phosphate aldolase. Results with mutants which are unable to metabolize L-rhamnose suggest the presence of an L-rhamnose I-phosphate phosphatase, which forms free L-rhamnose by hydrolysis of L-rhamnose I-phosphate produced by the phosphotransferase system. Mutants which lack this enzyme exhibited severe inhibition of growth in the presence of L-rhamnose plus any of a variety of carbon sources. There is some evidence that this inhibition was due to accumulation of L-rhamnose I-phosphate at toxic concentrations within the bacteria. The metabolism of L-rhamnose transported by the phosphotransferase system therefore appears to occur by hydrolysis of L-rhamnose I-phosphate to free L-rhamnose by a phosphatase. Metabolism of the L-rhamnose thus produced, and of that accumulated by the respiration-coupled transport system, the proceeds by the sequence of reactions: L-rhamnose leads to L-rhamnulose leads to L=rhamnulose I-phosphate leads to dihydroxyacetone phosphate plus L-lactaldehyde.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aldehyde-Lyases / metabolism
  • Arthrobacter / enzymology
  • Arthrobacter / metabolism*
  • Carbohydrate Epimerases / metabolism
  • Fructose / metabolism
  • Hexosephosphates / metabolism
  • Malates / metabolism
  • Mutation
  • Phosphotransferases / metabolism
  • Rhamnose / metabolism*
  • Stereoisomerism

Substances

  • Hexosephosphates
  • Malates
  • Fructose
  • Phosphotransferases
  • Aldehyde-Lyases
  • Carbohydrate Epimerases
  • Rhamnose