Dihydrolipoyllysine-residue acetyltransferase component of pyruvate dehydrogenase complex, mitochondrial

UniProtKB accession:  G0S4X6

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UniProtKB description:  The 10-megadalton pyruvate dehydrogenase complex contains multiple copies of three enzymatic components: pyruvate dehydrogenase (E1), dihydrolipoamide acetyltransferase (E2) and lipoamide dehydrogenase (E3) and catalyzes the overall oxidative decarboxylation of pyruvate to form acetyl-CoA and CO(2) (PubMed:33567276, PubMed:34836937, PubMed:35093201). Within the complex, pyruvate and thiamine pyrophosphate (TPP or vitamin B1) are bound by pyruvate dehydrogenase E1 subunits alpha and beta and pyruvate is decarboxylated leading to the 2-carbon hydrohyethyl bound to TPP. The E2 component contains covalently-bound lipoyl cofactors and transfers the hydroxyethyl group from TPP to an oxidized form of covalently bound lipoamide, and the resulting acetyl group is then transferred to free coenzyme A to form acetyl-CoA and reduced dihydrolipoamide-E2. Finally, the flavoprotein dihydrolipoamide dehydrogenase (E3) re-oxidizes the lipoyl group of dihydrolipoamide-E2 to form lipoamide-E2 and NADH. A fourth subunit, E3BP, is responsible for tethering E3 in proximity to the core, forming the entire metabolon (Probable).