If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Locations of Mapped Genes:
Synonyms: rhamnose catabolism, rhamnose degradation
|Superclasses:||Degradation/Utilization/Assimilation → Carbohydrates Degradation → Sugars Degradation → L-rhamnose Degradation|
Via reactions catalyzed by proteins encoded in linked operons comprising a regulon, the methylpentose, rhamnose, is taken into the cell and metabolized, enabling E. coli to grow on it as a total source of carbon and energy. An isomerase and subsequent kinase convert rhamnose to rhamnulose-1-phosphate, which is cleaved by a specific aldolase into dihydroxyacetone phosphate (an intermediate of glycolysis, which thereby enters central metabolism), and (S)-lactaldehyde. L-fucose, the other methylpentose that E. coli can utilize, is metabolized by an analogous series of reactions (see fucose degradation).
Two pathways can be used for degradation of L-lactaldehyde. Aerobically, it is converted via lactate to pyruvate, also an intermediate of glycolysis. Anaerobically, lactaldehyde reductase is induced which converts lactaldehyde into propane-1,2-diol. E. coli excretes propane-1,2-diol into the medium.
An overview of fucose and rhamnose degradation is shown in the superpathway of fucose and rhamnose degradation.
Review: Mayer, C. and W. Boos, Hexose/Pentose and Hexitol/Pentitol Metabolism. EcoSal Module 3.4.1 [ECOSAL]
Superpathways: superpathway of fucose and rhamnose degradation
Badia91: Badia J, Gimenez R, Baldoma L, Barnes E, Fessner WD, Aguilar J (1991). "L-lyxose metabolism employs the L-rhamnose pathway in mutant cells of Escherichia coli adapted to grow on L-lyxose." J Bacteriol 1991;173(16);5144-50. PMID: 1650346
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
GarciaJunceda95: Garcia-Junceda E, Shen GJ, Sugai T, Wong CH (1995). "A new strategy for the cloning, overexpression and one step purification of three DHAP-dependent aldolases: rhamnulose-1-phosphate aldolase, fuculose-1-phosphate aldolase and tagatose-1,6-diphosphate aldolase." Bioorg Med Chem 3(7);945-53. PMID: 7582972
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