Fermentation and alternative respiration compensate for NADH dehydrogenase deficiency in a prokaryotic model of DJ-1-associated Parkinsonism

Abstract

YajL is the closest prokaryotic homologue of Parkinson's disease-associated DJ-1, a protein of undefined function involved in the oxidative stress response. We reported recently that YajL and DJ-1 protect cells against oxidative stress-induced protein aggregation by acting as covalent chaperones for the thiol proteome, including the NuoG subunit of NADH dehydrogenase 1, and that NADH dehydrogenase 1 activity is negligible in the yajL mutant. We report here that this mutant compensates for low NADH dehydrogenase activity by utilizing NADH-independent alternative dehydrogenases, including pyruvate oxidase PoxB and D-amino acid dehydrogenase DadA, and mixed acid aerobic fermentations characterized by acetate, lactate, succinate and ethanol excretion. The yajL mutant has a low adenylate energy charge favouring glycolytic flux, and a high NADH/NAD ratio favouring fermentations over pyruvate dehydrogenase and the Krebs cycle. DNA array analysis showed upregulation of genes involved in glycolytic and pentose phosphate pathways and alternative respiratory pathways. Moreover, the yajL mutant preferentially catabolized pyruvate-forming amino acids over Krebs cycle-related amino acids, and thus the yajL mutant utilizes pyruvate-centred respiro-fermentative metabolism to compensate for the NADH dehydrogenase 1 defect and constitutes an interesting model for studying eukaryotic respiratory complex I deficiencies, especially those associated with Alzheimer's and Parkinson's diseases.

Iron‐sulfur cluster carrier proteins involved in the assembly of Escherichia coli NADH:ubiquinone oxidoreductase (complex I)

“…Strain BW25113 Δ ndh Δ bolA showed no significant change of NADH and succinate oxidase activities, while both were slightly but significantly decreased by 20% in strain BW25113 Δ ndh Δ yajL . Deletion of yajL was reported to result in an upregulation of other dehydrogenases (Messaoudi et al ., ). Indeed, the formate oxidase activity caused by the formate dehydrogenase expressed under oxic conditions (Fdh‐O) was with 0.18 U mg –1 in the Δ yajL deletion strain twice the value obtained with the parental strain.…”

“…Cysteine residues that are ligands of Fe/S clusters were proposed to be protected by YajL due to the formation of mixed disulfides. The deletion of yajL was reported to lead to a more than sevenfold reduction of the artificial d‐NADH/2,6‐dichlorophenolindophenol (DCPIP) oxidoreductase activity of E. coli membranes, which is interpreted as a 82% loss of complex I (Le et al ., ; Messaoudi et al ., ). However, the physiological NADH oxidase activity of the yajL deletion strain was decreased just by 22% indicating a much milder effect of the mutation on complex I than proposed (Table ).…”

“…Deleting yajL did not lead to the loss of a binuclear cluster indicating that YajL might act on the tetranuclear Fe/S clusters. It was proposed that the loss of YajL results in high cellular NADH/NAD + ratio caused by the complex I deficiency that is compensated by upregulation of other dehydrogenases of mixed acid aerobic fermentation (Messaoudi et al, 2015). Indeed, membranes from the ΔyajL strain show a twofold higher formate oxidase activity indicating a metabolic switch to alternative dehydrogenases (e.g.…”

“…An error of ± 5-8% was determined. The NADH/DCPIP assay was performed as described (Messaoudi et al, 2015).…”

“…YajL is a multi-functional oxidative stress response protein that exhibits chaperone activity (Sastry et al, 2002;Gautier et al, 2012). It was reported that deletion of yajL leads to a decrease complex I activity and an overproduction of alternative dehydrogenases (Messaoudi et al, 2015).…”