Characterization of the P450 Monooxygenase LobP1 as C-32 Hydroxylase in
Lobophorin Biosynthesis
Abstract
Lobophorins (LOBs) belong to a large family of spirotetronate
antibiotics with antibacterial and antitumor activities. In this study,
we demonstrated the function of LobP1, a P450 monooxygenase encoded in
the LOB biosynthetic gene cluster, by in vivo deletion and in vitro
biochemical assays. The disruption of lobP1 led to the isolation of
three new LOBs derivatives (3‒5) and three known ones (6‒8) without the
hydroxyl group at C-32. LobP1 was shown to have relatively broad
substrate scope. Determing the kinetic parameters of LobP1 towards
different substrates revealed that LobP1 preferred substrate with a
nitrosugar. The major product LOB E (6) from the ∆lobP1 mutant displayed
better cytotoxic activities against several cancer cell lines than LOB
B, the C-32 hydroxlated counterpart.