Pyruvate dehydrogenase kinase from Arabidopsis thaliana: a protein histidine kinase that phosphorylates serine residues

Abstract

Pyruvate dehydrogenase kinase (PDK) is the primary regulator of flux through the mitochondrial pyruvate dehydrogenase complex (PDC). Although PDKs inactivate mitochondrial PDC by phosphorylating specific Ser residues, the primary amino acid sequence indicates that they are more closely related to prokaryotic His kinases than to eukaryotic Ser/Thr kinases. Unlike Ser/Thr kinases, His kinases use a conserved His residue for phosphotransfer to Asp residues. To understand these unique kinases better, a presumptive PDK from Arabidopsis thaliana was heterologously expressed and purified for this investigation. Purified, recombinant A. thaliana PDK could inactivate kinase-depleted maize mitochondrial PDC by phosphorylating Ser residues. Additionally, A. thaliana PDK was capable of autophosphorylating Ser residues near its N-terminus, although this reaction is not part of the phosphotransfer pathway. To elucidate the mechanism involved, we performed site-directed mutagenesis of the canonical His residue likely to be involved in phosphotransfer. When His-121 was mutated to Ala or Gln, Ser-autophosphorylation was decreased by 50% and transphosphorylation of PDC was decreased concomitantly. We postulate that either (1) His-121 is not the sole phosphotransfer His residue or (2) mutagenesis of His-121 exposes an additional otherwise cryptic phosphotransfer His residue. Thus His-121 is one residue involved in kinase function.

Disruption of genes encoding pyruvate dehydrogenase kinases leads to retarded growth on acetate and ethanol in Saccharomyces cerevisiae

“…Similar regulation mechanisms of PDH activity may occur in plants (Thelen et al, 1998(Thelen et al, , 2000Zou et al, 1999). The situation in S. cerevisiae is less clear.…”

Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO2 Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

“…Based on these findings, we predict that transgenic approaches applied in K. fedtschenkoi will also prove useful for demonstrating the functional role of other proposed CAM regulators, such as PPDK regulatory protein (Dever et al, 2015), or pyruvate dehydrogenase kinase (Thelen et al, 2000), or as yet unknown transcription factors and other regulatory proteins that likely function in the circadian clock output pathway that couples the core molecular oscillator to the regulation of CAM enzymes via proteins such as PPCK (Hartwell, 2006;Borland et al, 2009;Hartwell et al, 2016).…”

Two-Component Signaling Elements and Histidyl-Aspartyl Phosphorelays†

“…Pyruvate dehydrogenase kinase retains the most highly conserved residues found in histidine kinases, but has nevertheless diverged significantly in other residues, resulting in an ability to phosphorylate its substrate, pyruvate dehydrogenase, at a serine residue (Thelen et al, 2000).…”