Cytosolic GAPDH as a redox-dependent regulator of energy metabolism

Abstract

BackgroundPlant cytosolic NAD-dependent glyceraldehyde-3-phosphate dehydrogenase (GapC) displays redox-dependent changes in its subcellular localizations and activity. Apart from its fundamental role in glycolysis, it also exhibits moonlighting properties. Since the exceptional redox-sensitivity of GapC has been suggested to play a crucial role in its various functions, we here studied its redox-dependent subcellular localization and the influence of the redox-state on GapC protein interactions.ResultsIn mesophyll protoplasts from Arabidopsis thaliana, colocalization of GapC with mitochondria was more pronounced under reducing conditions than upon oxidative stress. In accordance, reduced GapC showed an increased affinity to the mitochondrial voltage-dependent anion-selective channel (VDAC) compared to the oxidized one. On the other hand, nuclear localization of GapC was increased under oxidizing conditions. The essential role of the catalytic cysteine for nuclear translocation was shown by using the corresponding cysteine mutants. Furthermore, interaction of GapC with the thioredoxin Trx-h3 as a candidate to revert the redox-modifications, occurred in the nucleus of oxidized protoplasts. In a yeast complementation assay, we could demonstrate that the plant-specific non-phosphorylating glyceraldehyde 3-P dehydrogenase (GapN) can substitute for glucose 6-P dehydrogenase to generate NADPH for re-reduction of the Trx system and ROS defense.ConclusionsThe preferred association of reduced, glycolytically active GapC with VDAC suggests a substrate-channeling metabolon at the mitochondrial surface for efficient energy generation. Increased occurrence of oxidized GapC in the nucleus points to a function in signal transduction and gene expression. Furthermore, the interaction of GapC with Trx-h3 in the nucleus indicates reversal of the oxidative cysteine modification after re-establishment of cellular homeostasis. Both, energy metabolism and signal transfer for long-term adjustment and protection from redox-imbalances are mediated by the various functions of GapC. The molecular properties of GapC as a redox-switch are key to its multiple roles in orchestrating energy metabolism.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1390-6) contains supplementary material, which is available to authorized users.

Arabidopsis Voltage-Dependent Anion Channels (VDACs): Overlapping and Specific Functions in Mitochondria

“…Interactions with glycolytic enzymes would favor the channeling of metabolites to mitochondria, but these interactions appear to be redox-dependant. Wojtera-Kuritz et al and Schneider et al have proposed that these interactions would be involved in adaptation to oxidative stress [36,39]. It is thus tempting to propose that stress, by inducing VDAC3 long mRNA, would induce a quick translation of VDAC3 at MOM, thus favoring its interaction with glycolytic enzymes or other proteins, and finally a quick response to stress.…”

Investigation of Heterologously Expressed Glucose-6-Phosphate Dehydrogenase Genes in a Yeast zwf1 Deletion

“…Plasmids expressing ZWF1 from S. cerevisiae or its homologs from other organisms were obtained by cloning either PCR products (for S. cerevisiae and K. lactis) or synthetic DNA-fragments under the control of a modified constitutive PFK2 promoter into the centromeric plasmid pJJH2064 [51]. Plasmids employed with their pJJH numbers are listed in Table 2, and their complete sequences are available upon request.…”

Rapid single-step affinity purification of HA-tagged mitochondria from Arabidopsis thaliana

“…Other notable OMM proteins identified in our proteomic data set included GTPases MIRO1 and MIRO2, lipid biosynthesis protein PECT, and β-barrel proteins VDAC1–4 (Supplemental Table S1, Supplemental Table S2). Recently, it was shown that the cytosolic protein GAPC interacts with VDAC (Schneider et al, 2018); we also identified GAPC in our proteomic data set.…”