CLONING, ANALYSIS, AND OVEREXPRESSION OF THE GENE ENCODING ISOBUTYLAMINE N-HYDROXYLASE FROM THE VALANIMYCIN PRODUCER, STREPTOMYCES-VIRIDIFACIENS

The flavoprotein isobutylamine N-hydroxylase (IBAH) catalyzes the oxid ation of isobutylamine to isobutyl-hydroxylamine, a key step in the bi osynthesis of the azoxy antibiotic valanimycin. By using oligonucleoti de primers designed from peptide sequence information derived from nat ive IBAH, a fragment of the gene (vlmH) encoding IBAH was amplified by PCR from a genomic library of the valanimycin-producing organism, Str eptomyces viridifaciens MG456-hF10. The gene fragment was then employe d as a probe to clone the entire vlmH gene from an S. viridifaciens ge nomic library, Overexpression of the vlmH gene in Escherichia coli gav e a soluble protein that was purified to homogeneity. The purified pro tein exhibited the catalytic activity expected for IBAH, The deduced a mino acid sequence of IBAH exhibited the greatest similarity to the So x/DszC protein from Rhodococcus sp, strain IGT38, a flavoprotein invol ved in the oxidation of dibenzothiophene to the corresponding Sulfone, Significant similarities were also found between the amino acid seque nce of IBAH and those of the acyl coenzyme A dehydrogenases.