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Structural and functional impact of clinically relevant E1α variants causing pyruvate dehydrogenase complex
Hana Pavlu-Pereira1, Diana Lousa2, Catarina S Tomé3
1Research Institute for Medicines (iMed.ULisboa) and Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal.
Biochimie
|February 15, 2021
Summary
Pyruvate dehydrogenase complex (PDC) deficiency impairs energy metabolism. Variants in the PDHA1 gene reduce enzyme activity and thiamine pyrophosphate (TPP) binding, complicating therapy development.
Area of Science:
- Biochemistry
- Metabolic disorders
- Molecular biology
Background:
- Pyruvate dehydrogenase complex (PDC) is crucial for linking glycolysis and the TCA cycle.
- PDC deficiency, often caused by PDHA1 mutations, presents a wide range of neurological and metabolic symptoms.
- Therapeutic strategies require understanding the biophysical impact of pathogenic variants.
Purpose of the Study:
- To characterize clinically relevant PDC-E1α variants found in Portuguese patients.
- To investigate the structural and functional consequences of these mutations.
- To assess the potential for developing targeted therapies for PDC deficiency.
Main Methods:
- Biophysical and structural analysis of recombinant heterotetrameric PDC-E1 variants.
- Molecular dynamics (MD) simulations to assess protein stability and cofactor binding.
- Enzymatic activity assays and thiamine pyrophosphate (TPP) binding affinity measurements.
Main Results:
- Pathogenic variants showed limited impact on overall conformational stability, except for increased aggregation of p.R253G.
- All variants exhibited reduced PDC-E1 enzymatic activity and significantly lower affinity for TPP.
- MD simulations indicated decreased stability, particularly in the TPP binding region, for all variants.
Conclusions:
- PDHA1 variants impair PDC function primarily through reduced TPP binding affinity and enzymatic activity.
- The observed biophysical changes correlate with disease severity in patients.
- Developing effective chaperone-based therapies for PDC deficiency remains challenging due to these functional impairments.
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