Database of articles cited by EMDB/PDB/SASBDB data

Keywords
Structure methods	All X-ray diffraction NMR electron microscopy small angle scattering neutron diffraction fiber diffraction powder diffraction infrared spectroscopy EPR fluorescence transfer theoretical model Hybrid
Author
Journal
IF	>30 >20 >10 >5 all

Title	A milestone in C4 carbon concentration mechanism evolution: structural remodeling of NADP-malic enzyme in Poaceae.
Journal, issue, pages	Mol Biol Evol, Vol. 43, Issue 4, Year 2026
Publish date	Apr 1, 2026
Authors	Jonas M Böhm / Simone Willms / Oja Ferrao / Martin Buitrago-Arango / Meike Hüdig / Gereon Poschmann / Nazanin Fazelnia / Luitgard Nagel-Steger / Sebastián Klinke / Athina Drakonaki / Christos Gatsogiannis / Marcos A Tronconi / Clarisa E Alvarez / Veronica G Maurino /
PubMed Abstract	The evolution of C4 photosynthesis required extensive modification of ancestral enzymes enabling the development of an efficient carbon concentrating mechanism. A key example is NADP-malic enzyme ...The evolution of C4 photosynthesis required extensive modification of ancestral enzymes enabling the development of an efficient carbon concentrating mechanism. A key example is NADP-malic enzyme (NADP-ME), which, in maize and sorghum-members of the same C4 lineage-underwent gene duplication and neofunctionalization, resulting in 2 plastidic isoforms with distinct oligomeric states: a tetrameric C4-specific isoform and a dimeric housekeeping (nonC4) isoform. In this study, we resolve the structural basis of this oligomeric divergence using X-ray crystallography, cryo-electron microscopy, and molecular modeling combined with targeted biochemical analysis. Our findings demonstrate that the N-terminal region of nonC4-NADP-ME is involved in its oligomeric organization, whereas a suite of adaptive substitutions at the dimer interface drives the transition to the stable tetramer characteristic of the C4 isoform. Moreover, the C-terminal region stabilizes the oligomeric states of C4- and nonC4-NADP-ME through specific interactions with adaptive residues. We propose that tetramerization mitigates aggregation at the high expression levels demanded by the C4 cycle and likely creates a scaffold for the emergence of regulatory properties. Collectively, the data show that remodeling of terminal domains and inter-subunit interfaces rewires the quaternary architecture of the enzymes, illustrating how subtle structural changes can drive the evolution of complex innovations such as C4 photosynthesis.
External links	Mol Biol Evol / PubMed:42017302 / PubMed Central
Methods	EM (single particle) / X-ray diffraction
Resolution	2.7 - 8.5 Å
Structure data	EMDB-56440: CryoEM map of chloroplastic photosynthetic NADP(+)-dependent malic enzyme Method: EM (single particle) / Resolution: 3.17 Å EMDB-56441: CryoEM map of chloroplastic photosynthetic NADP(+)-dependent malic enzyme mutant (G200R) at pH 8 Method: EM (single particle) / Resolution: 5.5 Å EMDB-56442: CryoEM map of chloroplastic photosynthetic NADP(+)-dependent malic enzyme mutant (G200R) at pH 4.8 Method: EM (single particle) / Resolution: 7.7 Å EMDB-56443: CryoEM map of dimeric non-photosynthetic NADP(+)-dependent malic enzyme Method: EM (single particle) / Resolution: 6.8 Å EMDB-56444: CryoEM map of tetrameric non-photosynthetic NADP(+)-dependent malic enzyme Method: EM (single particle) / Resolution: 8.5 Å PDB-9e6m: Crystal structure of the G200R mutant from the maize chloroplastic photosynthetic NADP(+)-dependent malic enzyme Method: X-RAY DIFFRACTION / Resolution: 2.7 Å
Chemicals	ChemComp-PYR: PYRUVIC ACID ChemComp-HOH: WATER
Source	zea mays (maize)
Keywords	PHOTOSYNTHESIS / malic enzyme / oxidative decarboxylase / NADP-dependent C4 photosynthesis