RELEASE OF GLUCOSE-MEDIATED CATABOLITE REPRESSION DUE TO A DEFECT IN THE MEMBRANE-FRACTION OF PHOSPHOENOLPYRUVATE - MANNOSE PHOSPHOTRANSFERASE SYSTEM IN PEDIOCOCCUS-HALOPHILUS

A spontaneous mutant 9R-4 resistant to 2-deoxyglucose (2DG) was derived from a wild-type strain Pediococcus halophilus I-13. Phosphoenolpyruvate (PEP)-dependent glucose-6-phosphate formation by the permeabilized 9R-4 cells was < 5% of that observed with the parent I-13. In vitro complementation of PEP-dependent 2DG-6-phosphate formation was assayed with combination of the cytoplasmic and membrane fractions prepared from the I-13 and the mutants (9R-4, and X-160 isolated from nature), which were defective in PEP: mannose phosphotransferase system (man:PTS). The defects in man:PTS of both the strain 9R-4 and X-160 were restricted to the membrane fraction (e.g. EII(man)), not to the cytoplasmic one. Kinetic studies on the glucose transport with intact cells and iodoacetate-treated cells also supported the presence of two distinct transport systems in this bacterium as follows: (i) The wild-type I-13 possessed a high-affinity man:PTS (K(m) = 11-mu-M) and a low-affinity proton motive force driven glucose permease (GP) (K(m) = 170-mu-M). (ii) Both 9R-4 and X-160 had only the low-affinity system (K(m) = 181-mu-M for 9R-4, 278-mu-M for X-160). In conclusion, a 2DG-induced selective defect in the membrane component (EII(man)) of the man:PTS could partially release glucose-mediated catabolite repression but not fructose-mediated catabolite repression in soy pediococci.