IDENTIFICATION OF THE GALE GENE AND A GALE HOMOLOG AND CHARACTERIZATION OF THEIR ROLES IN THE BIOSYNTHESIS OF LIPOPOLYSACCHARIDE IN A SEROTYPE O 8 STRAIN OF YERSINIA-ENTEROCOLITICA/

A clone that complements mutations in Yersinia enterocolitica lipopoly saccharide (LPS) core biosynthesis was isolated, and the DNA sequence of the clone was determined, Three complete open reading frames and on e partial open reading frame were located on the cloned DNA fragment, The first, partial, open reading frame had homology to the rfbK gene, The remaining reading frames had homology to galE, rol, and gsk, Analy sis of the galE homolog indicates that although it can complement an E scherichia coli galE mutant, its primary function in Y. enterocolitica is not in the production of UDP galactose but, instead, some other nu cleotide sugar required for LPS biosynthesis. This gene has been renam ed Ise, for LPS sugar epimerase, The rol homolog has been demonstrated to have a role in Y. enterocolitica serotype O:8 O-polysaccharide ant igen chain length determination, An additional galE homolog has been i dentified in Y. enterocolitica by homolog to the E. coli gene, The pro duct of this gene has UDP galactose 4-epimerase activity in both E. co li and Y. enterocolitica. This gene is linked to the other genes of th e galactose utilization pathway, similar to what is seen in other memb ers of the family Enterobacteriaceae. Although Y. enterocolitica O:8 s trains are reported to have galactose as a constituent of LPS, a strai n containing a mutation in this galE gene does not exhibit any LPS def ects.