8XTG

Crystal structure of methyltransferase MpaG' in complex with SAH and DMMPA

This is a non-PDB format compatible entry.

Summary for 8XTG

• Entry DOI: 10.2210/pdb8xtg/pdb
• Related: 8XTE 8XTF
• Descriptor: O-methyltransferase mpaG', S-ADENOSYL-L-HOMOCYSTEINE, O-desmethyl mycophenolic acid, ... (4 entities in total)
• Functional Keywords: methyltransferase, mpag', mpa biosynthesis, biosynthetic protein
• Biological source: Penicillium brevicompactum
• Total number of polymer chains: 6
• Total formula weight: 266302.82

Authors

You, C.,Pan, Y.J.,Li, S.Y.,Feng, Y.G. (deposition date: 2024-01-10, release date: 2024-08-28)

Primary citation

You, C.,Pan, Y.,Liu, R.,Li, S.,Feng, Y.
Structural basis for substrate flexibility of the O-methyltransferase MpaG' involved in mycophenolic acid biosynthesis.
Protein Sci., 33:e5144-e5144, 2024

PubMed Abstract: MpaG' is an S-adenosyl-L-methionine (SAM)-dependent methyltransferase involved in the compartmentalized biosynthesis of mycophenolic acid (MPA), a first-line immunosuppressive drug for organ transplantations and autoimmune diseases. MpaG' catalyzes the 5-O-methylation of three precursors in MPA biosynthesis including demethylmycophenolic acid (DMMPA), 4-farnesyl-3,5-dihydroxy-6-methylphthalide (FDHMP), and an intermediate containing three fewer carbon atoms compared to FDHMP (FDHMP-3C) with different catalytic efficiencies. Here, we report the crystal structures of S-adenosyl-L-homocysteine (SAH)/DMMPA-bound MpaG', SAH/FDHMP-3C-bound MpaG', and SAH/FDHMP-bound MpaG' to understand the catalytic mechanism of MpaG' and structural basis for its substrate flexibility. Structural and biochemical analyses reveal that MpaG' utilizes the catalytic dyad H306-E362 to deprotonate the C5 hydroxyl group of the substrates for the following methylation. The three substrates with differently modified farnesyl moieties are well accommodated in a large semi-open substrate binding pocket with the orientation of their phthalide moiety almost identical. Based on the structure-directed mutagenesis, a single mutant MpaG' is engineered with significantly improved catalytic efficiency for all three substrates. This study expands the mechanistic understanding and the pocket engineering strategy for O-methyltransferases involved in fungal natural product biosynthesis. Our research also highlights the potential of O-methyltransferases to modify diverse substrates by protein design and engineering.

PubMed: 39150221
DOI: 10.1002/pro.5144

Experimental method

X-RAY DIFFRACTION (2 Å)