Functional characterization of MpaG′, the O-methyltransferase involved in the biosynthesis of mycophenolic acid
Mycophenolic acid (MPA, 1) is a clinically important immunosuppressant. In this report, a gene cluster mpa′' responsible for the biosynthesis of 1 was identified from Penicillium brevicompactum NRRL 864. The S-adenosyl-L-methionine-dependent (SAM-dependent) O-methyltransferase encoded by the mpaG′ gene was functionally and kinetically characterized in vitro. MpaG′ catalyzes the methylation of demethylmycophenolic acid (DMMPA, 6) to form 1. It also showed significant substrate flexibility by methylating two structural derivatives of 6 prepared by organic synthesis.
Mycophenolic acid (MPA), known as an inhibitor of inosine monophosphate dehydrogenase (IMPDH), was found to inhibit the differentiation of 3T3-L1 pre-adipocytes into mature adipocytes. Although the effect of MPA was attributed to inhibition of IMPDH, we u