CLONING AND CHARACTERIZATION OF A PAIR OF GENES THAT STIMULATE THE PRODUCTION AND SECRETION OF ZYMOMONAS-MOBILIS EXTRACELLULAR LEVANSUCRASEAND INVERTASE

A 1.7-kb DNA fragment cloned from Zymomonas mobilis genomic DNA comple mented the inability to grow on sucrose of a Suc- mutant of Z. mobilis that was deficient in the production of both extracellular levansucra se and invertase. Analysis of the nucleotide sequence of the fragment found two open reading frames (ORFs), both of which did not correspond to the structural gene for the levansucrase or the invertase. By subc loning each ORF into two different Suc- mutants of Z. mobilis, it has been found that the first ORF (gene zliE) activates the production of the extracellular levansucrase and invertase, and the second ORF (gene zliS) stimulates the secretion of the two enzymes. Gene zliS might co ntribute to the secretion of proteins having no signal peptide. The ex pression of zliE and zliS seemed to be under the control of the same p romoter.