Genetic analysis of the acetan biosynthetic pathway in Acetobacter xylinum: nucleotide sequence analysis of the aceB, aceC, aceD and aceE genes.

Sequence analysis of a 5.323 kb chromosomal DNA fragment from Acetobacter xylinum involved in the biosynthesis of the exopolysaccharide acetan, revealed the presence of four ace genes designated aceB, aceC, aceD and aceE. Comparison of translated gene sequences to the databanks was used to assign putative gene functions. AceB displayed strong homology to a glucose-diphosphoprenyl beta, D-glucose transferase from Xanthomonas campestris, while AceC was homologous to a cellobiosyl-diphosphoprenyl alpha, D-mannose transferase from the same organism. Thus these genes encode enzymes catalyzing the second and third steps of the acetan biosynthetic pathway. AceD and AceE were homologous to ExoP and ExoT respectively from Rhizobium meliloti and are likely to be involved in acetan polymerization and export.