The aminoglycoside phosphotransferases achieve inactivation of their antibiotic substrates by phosphorylation. Only phosphorylates hygromycin and closely related compounds such as demethyl analogs and destomycin. ATP + hygromycin B = 4-O-phosphohygromycin B + ADP + H(+) Hygromycin B resistant E.coli were found to contain a Klebsiella derived plasmid, pJR225. This plasmid contains the hph gene. Belongs to the aminoglycoside phosphotransferase family.