Nucleotide sequence of the transposon Tn7 gene encoding an aminoglycoside-modifying enzyme, 3"(9)-O-nucleotidyltransferase.

The nucleotide sequence of a transposon Tn7 DNA fragment encoding a 3"(9)-O-nucleotidyltransferase, an aminoglycoside-modifying enzyme, which mediates bacterial resistance to spectinomycin and streptomycin, was determined. The aadA structural gene was 786 bases long and predicted a polypeptide of 262 amino acids with a calculated molecular weight of 29,207. Comparison of the DNA sequences of Tn7 and plasmid R538-1 indicated that their aadA genes were nearly identical. Comparison of the polypeptides predicted by the aadA genes of Tn7 and Tn554 indicated that the genes were related.