Publicación en la revista Nature Plants

Investigadoras del CEFOBI lograron determinar la estructura tridimensional de la enzima málica, la cual es clave en el metabolismo fotosintético de maíz y sorgo. El trabajo permitió identificar los aminoácidos determinantes de la alta eficiencia catalítica, la estructura y la regulación específicas que adquirió esta enzima durante la evolución. El trabajo de las Dras. Alvarez, Saigo y Drincovich se realizó en colaboración con investigadores de la Universidad Heinrich Heine de Düsseldorf, el Instituto de Sistemas Complejos de Jülich y los Institutos Pasteur de Montevideo y Paris. Fue publicado hoy en la revista Nature Plants, una de las más prestigiosas del mundo.

 
Resumen del trabajo:
 

Molecular adaptations of NADP-malic enzyme for its function in C4 photosynthesis in grasses

 

Clarisa E. Alvarez, Anastasiia Bovdilova, Astrid Höppner, Christian-Claus Wolf, Mariana Saigo, Felipe Trajtenberg, Tao Zhang, Alejandro Buschiazzo, Luitgard Nagel-Steger, Maria F. Drincovich , Martin J. Lercher and Veronica G. Maurino

 

In C4 grasses of agronomical interest, malate shuttled into the bundle sheath cells is decarboxylated mainly by nicotinamide adenine dinucleotide phosphate (NADP)-malic enzyme (C4-NADP-ME). The activity of C4-NADP-ME was optimized by natural selection to efficiently deliver CO2 to Rubisco. During its evolution from a plastidic non-photosynthetic NADP-ME, C4-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 C4 adaptions based on strict differential conservation of amino acids, combined with solving the crystal structures of maize and sorghum C4-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 C4 metabolism.

 
Para ver el trabajo completo:
https://www.nature.com/articles/s41477-019-0451-7

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