RT Journal Article SR Electronic(1) A1 Levinson, Susan L. A1 Krulwich, Terry A.YR 1976 T1 Metabolism of l-Rhamnose in Arthrobacter pyridinolis JF Microbiology, VO 95 IS 2 SP 277 OP 286 DO https://doi.org/10.1099/00221287-95-2-277 PB Microbiology Society, SN 1465-2080, AB SUMMARY: 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 l-phosphate ( Levinson & Krulwich, 1974 ). The pathways for subsequent metabolism of l-rhamnose and l-rhamnose 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, then proceeds by the sequence of reactions: l-rhamnose →l-rhamnulose → l-rhamnulose i-phosphate → dihydroxyacetone phosphate plus l-lactaldehyde., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-95-2-277