Molecular cloning and sequence analysis of rfaF gene of Bradyrhizobium japonicum

초록

In a previous study, a nodulation-defective mutant strain of Bradyrhizobium japonicum was isolated and characterized. In this study the mutated gene region was cloned and characterized. DNA sequence analysis of a 3.0kb region revealed an open reading frame(orf1) of 1,065 bp which encodes a polypeptide of 354 amino acid residues with a molecular weight of 38,578 dalton. Search for homology with known gene sequence in a data bank revealed a significant sequence homology with rfaF gene cloned from E. coli, S.typhimurium and N.gonorrhoeae. In these bacteria, the rfaF gene was inferred to determine heptosyl transferase for transfer of heptose from ADP-heptose to the inner core of LPS. The sequence analysis data are in line with the phenotypic properties shown by the mutant strain.