Function
O-methyltransferase; part of the gene cluster that mediates the biosynthesis of mycophenolic acid (MPA), the first isolated antibiotic natural product in the world (PubMed:21398490, PubMed:22544261, PubMed:25630520). The first step of the pathway is the synthesis of 5-methylorsellinic acid (5MOA) by the polyketide synthase mpaC (PubMed:21398490). 5MOA is then converted to the phthalide compound 5,7-dihydroxy-4,6-dimethylphthalide (DHDMP) by mpaDE (PubMed:22544261). MpaDE first catalyzes hydroxylation of 5-MOA to 4,6-dihydroxy-2-(hydroxymethyl)-3-methylbenzoic acid (DHMB) (PubMed:22544261). MpaDE then acts as a lactone synthase that catalyzes the ring closure to convert DHMB is then converted to DHMP (PubMed:22544261). The next step is the prenylation of DHMP by the prenyltransferase mpaA to yield farnesyl-DHDMP (PubMed:25630520). Farnesyl-DHDMP might be a substrate of mpaH for transformation into demethylmycophenolic acid (DMMPA) (PubMed:25630520). Finally, the O-methyltransferase mpaG catalyzes the methylation DMMPA to form MPA (PubMed:25630520).
Sequence
MSAASPASIIQELASAAKQYENNESGAREALIAQSRALIASLEVPSEFIQHTFWSQPALSAIVRLATDVNLFQYLKDAQEEGLSAEALASKTGMDVSLFARLARHLVAMNVITSRNGVFYGTALSNGLAAENYQQSIRFCHDVSRPSFGAFPSFFKGNGYKTPALGTTDGPFQSAHKVDISFPQWLVGNPPYLQYFNSYMSAYRAGKPNWCDNGFYPVADRLLNGFDASVSDVLLVDVGGGRGHDIATFGSQFSPLPGRLVLQDREQVINSIPADESRQFEATTHDIFTTQPVKNARAYYMHSVPHGFGDEDAVKIMANLVPALAKGYSRVLLNEIVVDEESPVMSATNMDLIMLAHMGAKERTEADWRSILTRAGLKVVNIYSYPGVAESLIEAELA