Work

Inactivation of mitochondrial pyruvate dehydrogenase by singlet oxygen involves lipoic acid oxidation, side-chain modification and structural changes

Year: 2025

Type: article

Abstract: The multi-subunit pyruvate dehydrogenase complex (PDC) plays a crucial role in glucose oxidation as it determines whether pyruvate is used for mitochondrial oxidative phosphorylation or is converted to lactate for aerobic glycolysis . PDC contains multiple lipoic acid groups, covalently attached at lysine residues to give lipoyllysine, which are responsible for acyl group transfer and critical to complex activity. We have recently reported that both free lipoic acid , and lipoyllysine in alpha-keto glutarate dehydrogenase , are highly susceptible to singlet oxygen ( 1 O 2 )-induced oxidation. We therefore hypothesized that PDC activity and structure would be influenced by 1 O 2 (generated using Rose Bengal and light) via modification of the lipoyllysines and other residues. PDC activity was decreased by photooxidation , with this being dependent on light exposure, O 2 , the presence of Rose Bengal, and D 2 O consistent with 1 O 2 -mediated reactions. These changes were modulated by pre-illumination addition of free lipoic acid and lipoamide . Activity loss occurred concurrently with lipoyllysine and sidechain modification (determined by mass spectrometry) and protein aggregation (detected by SDS-PAGE). Peptide mass mapping provided evidence for modification at 42 residues (Met, Trp , His and Tyr ; with modification extents of 20–50 %) and each of the lipoyllysine sites (6–20 % modification). Structure modelling indicated the modifications occur across all 4 subunit types, and occur in functional domains or at multimer interfaces, consistent with damage at multiple sites contributing to the overall loss of activity. These data indicate that PDC activity and structure are susceptible to 1 O 2 -induced damage with potential effects on cellular pathways of glucose metabolism .

Source: Free Radical Biology and Medicine

DOI: 10.1016/j.freeradbiomed.2025.04.011

Authors: Qing Gao, Per Hägglund, Luke F. Gamon, Michael J. Davies

Institution: University of Copenhagen

Language: English

Topic: Biochemical Acid Research Studies

Subfield: Biochemistry

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: hybrid

Estimated APC paid: $4,240

Funders: China Scholarship Council, Novo Nordisk Fonden