Lysine acetylation of NADP-malic enzyme of Setaria viridis

RODRIGUEZ AIETA, CONSTANZA; CALACE, PAULA; GERRARD WHEELER, MARIEL CLAUDIA; SAIGO, MARIANA

Mendoza

Congreso; LVIII Reunión Anual SAIB; 2022

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Lysine acetylation is a post translational modification that serves as an important metabolic modulator in many organisms. In our investigation, we evaluate the hypothesis that acetylated lysines could have a prominent role in the modulation of the function of the photosynthetic C4 cycle in plants. Plants performing C4 photosynthesis have a higher productivity per crop area related to an optimized use of water and nutrients. This occurs because C4 plants partition photosynthetic reactions between two cell types. They initially fix the carbon to C4 acids within the mesophyll cells (MC) and then transport these compounds to bundle sheath cells (BSC), where they are decarboxylated. This carbon shuttle results in a more efficient incorporation of CO2 into the Calvin cycle because it allows CO2 concentration to increase in the RuBisCO environment. In previous analysis, we have investigated metabolic characteristics underlying the C4 cycle in Setaria viridis, a model plant closely related to several important forage and bioenergy grasses. We observed variations in acetyl-CoA producing pathways between BSC and MC. Since acetyl-CoA is a well-known acetyl-donor, in this work we searched the proteome data for lysine acetylated peptides. We found that NADP-dependent malic enzyme, a key enzyme in the C4 pathway, in BSC presents a N-acetylation-type modification in lysine 582. Furthermore, the immunoprecipitated NADP-ME from S. viridis leaf extract was recognised by anti-acetylated lysine antibodies. These results indicate that NADP-ME would be acetylated in vivo, which could impact on the catalytic characteristics thus functioning as a C4 photosynthesis modulator. To prove this hypothesis further experiments are needed, which are now under progress.