Construction of a new catabolic pathway for D-fructose in Escherichia coli K12 using an L-sorbose-specific enzyme from Klebsiella pneumoniae.

Starting with a fruK (formerly fpk) mutant of Escherichia coli K12 lacking D-fructose-1-phosphate kinase (E.C. 2.7.1.3.), fructose positive derivatives were isolated after introduction of the cloned gene sorE from Klebsiella pneumoniae coding for an L-sorbose-1-phosphate reductase. The new pathway was shwon to proceed from D-fructose via D-fructose-1-phosphate and D-mannitol-1-phosphate to D-fructose 6-phosphate. It involves a transport system and enzymes encoded in the fru and the mtl operons from E. coli K12 as well as in the sor operon from K. pneumoniae respectively.