Pyrimidine (PYR) binding domain of the beta subunits of the E1 components of human pyruvate dehydrogenase complex (E1- PDHc) and related proteins.
Thiamine pyrophosphate (TPP) family, pyrimidine (PYR) binding domain of the beta subunits of the E1 components of: human pyruvate dehydrogenase complex (E1- PDHc), the acetoin dehydrogenase complex (ADC), and the branched chain alpha-keto acid dehydrogenase/2-oxoisovalerate dehydrogenase complex (BCADC), subfamily. The PYR domain is found in many key metabolic enzymes which use TPP (also known as thiamine diphosphate) as a cofactor. TPP binds in the cleft formed by a PYR domain and a PP domain. The PYR domain, binds the aminopyrimidine ring of TPP, the PP domain binds the diphosphate residue. A polar interaction between the conserved glutamate of the PYR domain and the N1' of the TPP aminopyrimidine ring is shared by most TPP-dependent enzymes, and participates in the activation of TPP. The PYR and PP domains have a common fold, but do not share strong sequence conservation. The PP domain is not included in this sub-family. E1-PDHc is an alpha2beta2 dimer-of-heterodimers having two active sites lying between PYR and PP domains of separate subunits, the PYR domains are arranged on the beta subunit, the PP domains on the alpha subunits. PDHc catalyzes the irreversible oxidative decarboxylation of pyruvate to produce acetyl-CoA in the bridging step between glycolysis and the citric acid cycle. ADC participates in the breakdown of acetoin. BCADC catalyzes the oxidative decarboxylation of 4-methyl-2-oxopentanoate, 3-methyl-2-oxopentanoate and 3-methyl-2-oxobutanoate during the breakdown of branched chain amino acids.
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