4QDK

Crystal structure of magnesium protoporphyrin IX methyltransferase (ChlM) from Synechocystis PCC 6803 with bound SAH

Summary for 4QDK

• Entry DOI: 10.2210/pdb4qdk/pdb
• Related: 4QDJ
• Descriptor: Magnesium-protoporphyrin O-methyltransferase, S-ADENOSYL-L-HOMOCYSTEINE, GLYCEROL, ... (4 entities in total)
• Functional Keywords: methyltransferase, transferase, magnesium protoporphyrin ix, s-adenosyl homocysteine
• Biological source: Synechocystis sp.
• Total number of polymer chains: 2
• Total formula weight: 53312.61

Authors

Chen, X.,Wang, X.,Liu, L. (deposition date: 2014-05-14, release date: 2014-08-06, Last modification date: 2023-11-08)

Primary citation

Chen, X.,Wang, X.,Feng, J.,Chen, Y.,Fang, Y.,Zhao, S.,Zhao, A.,Zhang, M.,Liu, L.
Structural insights into the catalytic mechanism of Synechocystis magnesium protoporphyrin IX O-methyltransferase (ChlM).
J.Biol.Chem., 289:25690-25698, 2014

PubMed Abstract: Magnesium protoporphyrin IX O-methyltransferase (ChlM) catalyzes transfer of the methyl group from S-adenosylmethionine to the carboxyl group of the C13 propionate side chain of magnesium protoporphyrin IX. This reaction is the second committed step in chlorophyll biosynthesis from protoporphyrin IX. Here we report the crystal structures of ChlM from the cyanobacterium Synechocystis sp. PCC 6803 in complex with S-adenosylmethionine and S-adenosylhomocysteine at resolutions of 1.6 and 1.7 Å, respectively. The structures illustrate the molecular basis for cofactor and substrate binding and suggest that conformational changes of the two "arm" regions may modulate binding and release of substrates/products to and from the active site. Tyr-28 and His-139 were identified to play essential roles for methyl transfer reaction but are not indispensable for cofactor/substrate binding. Based on these structural and functional findings, a catalytic model is proposed.

PubMed: 25077963
DOI: 10.1074/jbc.M114.584920

Experimental method

X-RAY DIFFRACTION (1.7 Å)