AbstractPlants need to be able to rapidly and flexibly adjust their metabolism to changes their immediate environment. Since this necessity results from the sessile lifestyle of land plants, key mechanisms of orchestrating central metabolic acclimation are likely to have evolved early. Here we explore the role of lysine acetylation as a posttranslational modification to directly modulate metabolic function. First, we generate a lysine acetylome of the early divergent land plant Physcomitrium (Physcomitrella) patens. We identify 638 lysine acetylation sites, which were predominant in the mitochondria and plastids. A comparison with different angiosperms, including Arabidopsis thaliana, pinpoints lysine acetylation as conserved strategy in land plants. We focus on modified enzymes involved in mitochondrial central metabolism and select the mitochondrial malate dehydrogenase (mMDH), which acts as a hub of plant metabolic flexibility. In P. patens we detected a unique lysine acetylated site located next to one of the four acetylation sites detected in A. thaliana mMDH1. We assessed the kinetic behavior of recombinant A. thaliana and P. patens mMDHs with site-specifically incorporated acetyllysines. While the sites K325, K329 and K334 do not show any changes in the catalytic properties as assessed by oxaloacetate reduction activity, acetylation of A. thaliana mMDH1 at K170 markedly decreases its activity and acetylation of P. patens mMDH1 at K172 increases it. In both cases, acetylation induces modifications of the turnover number of the enzymes, without modifying the affinity for the substrates. Homology modelling of the mMDH1 proteins reveals a hotspot of lysine acetylation that is distant from the active site and homomerisation interfaces but conserved in land plants. The data reveal lysine acetylation as a strategy to tune the enzymatic properties of central metabolic enzymes with likely impact on metabolic capacity and flexibility to underpin plant acclimation.
Acetylation of conserved lysines fine‐tunes mitochondrial malate dehydrogenase activity in land plants
