Post-PKS Tailoring of Phoslactomycins Involving Two Cytochrome P450s

Combining in vivo and in vitro approaches, we elucidated the phoslactomycin post-PKS tailoring pathway in S. platensis. Gene inactivation of pnT1-pnT7 revealed seven phoslactomycin derivatives (four novel). Two cytochrome P450s were identified: PnT3 (mediating dual-site, multistep C-8/C-25 oxidation) and PnT7 (catalyzing C-18 hydroxylation). Activity evaluation established essential C-9 phosphate and detrimental ε-lactone/C-3 malonyl effects. These findings bridge the gap in phoslactomycin modification, highlighting a versatile P450 PnT3, and provide SAR foundations for PP2A inhibitor design.