THE DEFLUORINATION OF 4-DEOXY-4-FLUORO-D-GLUCOSE IN THE CYTOPLASMIC MEMBRANE OF PSEUDOMONAS-PUTIDA

The metabolism of 5 mM 4-deoxy-4-fluoro-D-glucose in Pseudomonas putid a to 4-deoxy-4-fluoro-D-gluconic and 4-deoxy-4-fluoro-D-arabino-2-hexu losonic acid is shown by F-19 NMR spectrometry to occur with concomita nt release of fluoride from each of these substrates. Gluconate-grown P. putida, incubated with 4-deoxy-4-fluoro-D-[U-Cl-14]glucose until 50 % fluoride ion is detected in the supernatant, gives 3,4-dideoxy-D-gly cero-2-hexulosonic acid, identified by C-13 NMR, chemical, and spectro photometric analyses. Although no fluoride release (F-) from 4FG is de tected in the outer membrane or periplasmic fractions of the cell enve lope, substantial F- is found in the cytoplasmic membrane (CM) fractio n in the presence of such electron donors as L-malate. CM detergent ex tracts contain a glucose-inducible, succinate-repressible protein havi ng an apparent molecular mass of 65 500. Reconstitution of CM extracts , derived from glucose- but not succinate-grown cells, with dipalmitoy lphosphatidylcholine gives proteoliposomes which elicit F- from 1 mM 4 FG. This F- release is totally inhibited by D-glucose but not by D-gal actose. The 65500 dalton protein is considered to be associated with t he active D-glucose transporter system in P. putida and responsible fo r the defluorination of 4FG.