6C7N

Monoclinic form of malic enzyme from sorghum at 2 angstroms resolution

Summary for 6C7N

• Entry DOI: 10.2210/pdb6c7n/pdb
• Descriptor: Malic enzyme, NADP NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE, GLYCEROL, ... (6 entities in total)
• Functional Keywords: enzyme substrate complex, oxidoreductase
• Biological source: Sorghum bicolor (Sorghum)
• Total number of polymer chains: 4
• Total formula weight: 274019.52

Authors

Trajtenberg, F.,Alvarez, C.,Buschiazzo, A. (deposition date: 2018-01-23, release date: 2019-01-30, Last modification date: 2023-11-15)

Primary citation

Alvarez, C.E.,Bovdilova, A.,Hoppner, A.,Wolff, C.C.,Saigo, M.,Trajtenberg, F.,Zhang, T.,Buschiazzo, A.,Nagel-Steger, L.,Drincovich, M.F.,Lercher, M.J.,Maurino, V.G.
Molecular adaptations of NADP-malic enzyme for its function in C4photosynthesis in grasses.
Nat.Plants, 5:755-765, 2019

PubMed Abstract: In C grasses of agronomical interest, malate shuttled into the bundle sheath cells is decarboxylated mainly by nicotinamide adenine dinucleotide phosphate (NADP)-malic enzyme (C-NADP-ME). The activity of C-NADP-ME was optimized by natural selection to efficiently deliver CO to Rubisco. During its evolution from a plastidic non-photosynthetic NADP-ME, C-NADP-ME acquired increased catalytic efficiency, tetrameric structure and pH-dependent inhibition by its substrate malate. Here, we identified specific amino acids important for these C adaptions based on strict differential conservation of amino acids, combined with solving the crystal structures of maize and sorghum C-NADP-ME. Site-directed mutagenesis and structural analyses show that Q503, L544 and E339 are involved in catalytic efficiency; E339 confers pH-dependent regulation by malate, F140 is critical for the stabilization of the oligomeric structure and the N-terminal region is involved in tetramerization. Together, the identified molecular adaptations form the basis for the efficient catalysis and regulation of one of the central biochemical steps in C metabolism.

PubMed: 31235877
DOI: 10.1038/s41477-019-0451-7

Experimental method

X-RAY DIFFRACTION (2 Å)