Three new polyketides from vasR2 gene over-expressed mutant strain of Verrucosispora sp. NS0172

Over-expression of the pathway specific positive regulator gene is an effective way to activate silent gene cluster. In the curret study, the SARP family regulatory gene, vasR2, was over-expressed in strain Verrucosispora sp. NS0172 and the cryptic gene cluster responsible for the biosynthesis of pentaketide ansamycin was partially activated. Two tetraketides ( 1 and 2 ) and a triketide ( 3 ) ansamycins, together with five known compounds ( 4 – 8 ), were isolated and elucidated from strain NS0172OEvasR2. Their NMR data were completely assigned by analysis of their HR-ESI-MS and ¹H, ¹³C NMR, HMQC, HMBC and ¹H-¹H COSY spectra.