A route for fructose utilization by Escherichia coli involving the fucose regulon

Fructose can be taken up by Escherichia coli via a variety of membrane-spanning proteins that recognize sugars with the 3,4,5-d-arabino-hexose configuration. Here, we describe a mutant that is devoid of those proteins but takes up fructose via the FucP carrier normally used for the transport of alpha-L-fucose; this implies that the fructose is taken up in the alpha- or beta-fructopyranose form. For growth, the assimilated fructose is sequentially phosphorylated by ATP and (i) manno(fructo)kinase, to form fructose 6-phosphate, and (ii) phosphofructokinase, to form fructose 1,6-bisphosphate, which is a member of central routes of glycolysis and gluconeogenesis. The mutation that confers on the organism the ability to take up fructose via the fucose regulon was located as a deletion of the fucA gene with consequent induction of the proton-linked fucose transporter, FucP.