Metabolism of D-arabinose: a new pathway in Escherichia coli.
Several growth characteristics of Escherichia coli K-12 suggest that growth on l-fucose results in the synthesis of all the enzymes necessary for growth on d-arabinose. Conversely, when a mutant of E. coli is grown on d-arabinose, all of the enzymes necessary for immediate growth on l-fucose are present. Three enzymes of the l-fucose pathway in E. coli, l-fucose isomerase, l-fuculokinase, and l-fuculose-l-phospháte aldolase possess activity on d-arabinose, d-ribulose, and d-ribulose-l-phosphate, respectively. The products of the aldolase, with d-ribulose-l-phosphate as substrate, are dihydroxyacetone phosphate and glycolaldehyde. l-Fucose, but not d-arabinose, is capable of inducing these activities in wild-type E. coli. In mutants capable of utilizing d-arabinose as sole source of carbon and energy, these activities are induced in the presence of d-arabinose and in the presence of l-fucose. Mutants unable to utilize l-fucose, selected from strains capable of growth on d-arabinose, are found to have lost the ability to grow on d-arabinose. Enzymatic analysis of cell-free extracts, prepared from cultures of these mutants, reveals that a deficiency in any of the l-fucose pathway enzymes results in the loss of ability to utilize d-arabinose. Thus, the pathway of d-arabinose catabolism in E. coli K-12 is believed to be: d-arabinose right harpoon over left harpoon d-ribulose --> d-ribulose-l-phosphate right harpoon over left harpoon dihydroxyacetone phosphate plus glycolaldehyde. Evidence is presented which suggests that the glycolaldehyde is further oxidized to glycolate.
D000446:Aldehyde-Lyases / Q000378:metabolism; D001089:Arabinose / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002474:Cell-Free System; D002854:Chromatography, Paper; D003124:Colorimetry; D003470:Culture Media; D004926:Escherichia coli / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D005643:Fucose / Q000378:metabolism; D005827:Genetics, Microbial; D006016:Glycolates / Q000096:biosynthesis; D007202:Indicators and Reagents; D007535:Isomerases / Q000378:metabolism; D009154:Mutation; D010770:Phosphotransferases / Q000378:metabolism; D013237:Stereoisomerism
D003470:Culture Media; D006016:Glycolates; D007202:Indicators and Reagents; D005643:Fucose; D001089:Arabinose; D010770:Phosphotransferases; D000446:Aldehyde-Lyases; D007535:Isomerases