GEL-ELECTROPHORETIC ANALYSIS OF ZYMOMONAS-MOBILIS GLYCOLYTIC AND FERMENTATIVE ENZYMES - IDENTIFICATION OF ALCOHOL DEHYDROGENASE-II AS A STRESS PROTEIN

The 13 major enzymes which compose the glycolytic and fermentative pathways in Zymomonas mobilis are particularly abundant and represent one-half of the soluble protein in exponential-phase cells. One- and two-dimensional polyacrylamide gel electrophoresis maps were developed for 12 of these enzymes. Assignments were made by comigration with purified proteins, comparison with overexpressed genes in recombinant strains, and Western blots (immunoblots). Although most glycolytic enzymes appeared resistant to turnover and accumulated in stationary-phase cells, the protein levels of pyruvate kinase, alcohol dehydrogenase I, and glucokinase declined. Alcohol dehydrogenase II was identified as a major stress protein and was induced both by exposure to ethanol and by elevated temperature (45-degrees-C). This enzyme, encoded by the adhB gene, is expressed from tandem promoters which share partial sequence identity with the Escherichia coli consensus sequence for heat shock proteins.