NUCLEOTIDE-SEQUENCE AND EXPRESSION OF UDP-GLUCOSE DEHYDROGENASE GENE REQUIRED FOR THE SYNTHESIS OF XANTHAN GUM IN XANTROMONAS-CAMPESTRIS

Xanthomonas campestris pv. campestris, producing large amounts of exop olysaccharide xanthan gum, has a mucoid phenotype. Strain SD7 was a no n-mucoid mutant deficient in UDP-glucose dehydrogenase. A DNA fragment able to complement the mutation of SD7 was cloned from the parental w ild-type strain Xc11. Sequence analysis of the region required for the complementation revealed an open reading frame which could encode a p olypeptide of 445 amino acids with a calculated molecular weight of 48 ,432, a size similar to that of the product produced by maxicell. The amino acid sequence had significant homology to that of the GDP-mannos e dehydrogenase from Pseudomonas aeruginosa. (C) 1995 Academic Press, Inc.