NUCLEOTIDE-SEQUENCE ANALYSIS OF 2 5-NITROIMIDAZOLE RESISTANCE DETERMINANTS FROM BACTEROIDES STRAINS AND OF A NEW INSERTION-SEQUENCE UPSTREAM OF THE 2 GENES

DNA sequence analysis of regions from plasmid pIP417 and chromosome BF 8 which encode 5-nitroimidazole resistance in Bacteroides strains allo wed the identification of two open reading frames corresponding to new genes, nimA (528 bp) and nimB (492 bp). Either gene may confer 5-nitr oimidazole resistance to susceptible strains of Bacteroides. The encod ed polypeptides have deduced molecular masses of 20.1 and 18.6 kDa, re spectively, and share about 73% identity and 85% similarity. A new ins ertion sequence (IS) element named IS1168 lies 14 bases upstream of th e nimA gene. The complete sequence of IS1168 was determined. A similar IS exists 12 bp upstream of the nimB gene. About 60% of the BF8 IS el ement was also sequenced and shown to be almost identical to IS1168.