Mapping of the sor genes for L-sorbose degradation in the chromosome of Klebsiella pneumoniae

Abstract

A series of mutants was isolated in Klebsiella pneumoniae strain 1033, among them mutants unable to grow on L-sorbose. Different R' plasmids carrying the sor genes and other surrounding chromosomal genes were also isolated. Each plasmid contained the structural genes sorA for an Enzyme II of the phosphoenolpyruvate-dependent carbohydrate:phosphotransferase system, sorD for a D-glucitol 6-phosphate dehydrogenase, sorE for an L-sorbose 1-phosphate reductase, and the corresponding regulator gene sorR. These structural genes are coordinately expressed and inducible by L-sorbose. Cis-dominant and pleiotropic mutations rendering the expression of the sor genes constitutive or eliminating it were isolated. Complementation of a series of mutations in Escherichia coli K12 and K. pneumoniae by various R' and F' plasmids and by P1 transduction in K. pneumoniae located the sor genes within the following gene sequence: rbs rha pfkA metB ppc argH ilv btuB rpoB metA ace sor pgi malB uvrA. The rbs-ilv gene loci tightly linked in E. coli K12 at 84 min, are separated in the map of K. pneumoniae 1033 and located at 86 and 89 min, respectively.