Fig. 3

In silico analysis of pyruvate dehydrogenase complex E1 p.R302H variant. Top left panel, cartoon and ribbon representation of the heterotetrameric PDC E1 crystallographic structure (PDB entry 3EXE). E1α subunit represented in green; E1β represented in blue; E1α phosphorylation loop A represented in orange. The corresponding E1α′ and E1β′ subunits are represented as a gray ribbon. Residues that are substituted in variants identified in Portuguese PDC deficient patients with mutations in PDHA1, encoding the PDH E1α subunit, are represented in sticks. Top right panel, scheme representing the possible impact of substituted residues in pathogenic E1α variants: p.R253G substitution located near phosphorylation loop A (orange shape); p.F205L substitution possibly affecting αα′ interface (each E1α subunit represented in different shades of green); p.R302H substitution located in phosphorylation loop A close to the TPP cofactor binding site; p.R378C/H substitutions located close to the αβ interface (each E1β subunit represented in different shades of blue), and possibly affecting the interaction with a domain of the PDC E2 component. Bottom panel, zoom-in on the region surrounding R302 (left), showing its possible interactions with neighbouring residues (Y287, R288, Y289, H290 and G298), only the latter being retained upon substitution by H in the p.R302H variant (right). Structural model of PDC-E1 p.R302H variant was obtained by loading the structure of WT PDC-E1 (PDB entry 3EXE) into Pymol and applying the mutagenesis tool to generate all possible rotamers of the substituting amino acid side chain