Defective function of α-ketoglutarate dehydrogenase exacerbates mitochondrial ATP deficits during complex I deficiency
Gerardo G. Piroli,
Allison M. Manuel,
Richard S. McCain,
Holland H. Smith,
Oliver Ozohanics,
Sara Mellid,
J. Hunter Cox,
William E. Cotham,
Michael D. Walla,
Alberto Cascón,
Attila Ambrus,
Norma Frizzell
Affiliations
Gerardo G. Piroli
Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
Allison M. Manuel
Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
Richard S. McCain
Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
Holland H. Smith
Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
Oliver Ozohanics
Department of Biochemistry, Institute of Biochemistry and Molecular Biology, Semmelweis University, Budapest, Hungary
Sara Mellid
Hereditary Endocrine Cancer Group, Spanish National Cancer Research Centre (CNIO), 28029, Madrid, Spain
J. Hunter Cox
Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
William E. Cotham
Mass Spectrometry Center, Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC, 29205, USA
Michael D. Walla
Mass Spectrometry Center, Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC, 29205, USA
Alberto Cascón
Hereditary Endocrine Cancer Group, Spanish National Cancer Research Centre (CNIO), 28029, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28029, Madrid, Spain
Attila Ambrus
Department of Biochemistry, Institute of Biochemistry and Molecular Biology, Semmelweis University, Budapest, Hungary
Norma Frizzell
Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA; Corresponding author. Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, 6439 Garners Ferry Road, Columbia, SC, 29209, USA.
The NDUFS4 knockout (KO) mouse phenotype resembles the human Complex I deficiency Leigh Syndrome. The irreversible succination of protein thiols by fumarate is increased in select regions of the NDUFS4 KO brain affected by neurodegeneration. We report that dihydrolipoyllysine-residue succinyltransferase (DLST), a component of the α-ketoglutarate dehydrogenase complex (KGDHC) of the tricarboxylic acid (TCA) cycle, is succinated in the affected regions of the NDUFS4 KO brain. Succination of DLST reduced KGDHC activity in the brainstem (BS) and olfactory bulb (OB) of KO mice. The defective production of KGDHC derived succinyl-CoA resulted in decreased mitochondrial substrate level phosphorylation (SLP), further aggravating the existing oxidative phosphorylation (OXPHOS) ATP deficit. Protein succinylation, an acylation modification that requires succinyl-CoA, was reduced in the KO mice. Modeling succination of a cysteine in the spatial vicinity of the DLST active site or introduction of succinomimetic mutations recapitulates these metabolic deficits. Our data demonstrate that the biochemical deficit extends beyond impaired Complex I assembly and OXPHOS deficiency, functionally impairing select components of the TCA cycle to drive metabolic perturbations in affected neurons.
