Function of several critical amino acids in human pyruvate dehydrogenase revealed by its structure.
Pyruvate dehydrogenase (E1), an alpha(2)beta(2) tetramer, catalyzes the oxidative decarboxylation of pyruvate and reductive acetylation of lipoyl moieties of the dihydrolipoamide acetyltransferase. The roles of betaW135, alphaP188, alphaM181, alphaH15, and alphaR349 of E1 determined by kinetic analysis were reassessed by analyzing the three-dimensional structure of human E1. The residues identified above are found to play a structural role rather than being directly involved in catalysis: betaW135 is in the center of the hydrophobic interaction between beta and beta' subunits; alphaP188 and alphaM181 are critical for the conformation of the TPP-binding motif and interaction between alpha and beta subunits; alphaH15 is necessary for the organization of the N-terminus of alpha and alpha' subunits; and alphaR349 supports the interaction of the C-terminus of the alpha subunits with the beta subunits. Analysis of several critical E1 residues confirms the importance of residues distant from the active site for subunit interactions and enzyme function.
Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14214, USA.
Lioubov G
LG
Korotchkina
Ewa M
EM
Ciszak
Mulchand S
MS
Patel
D000596:Amino Acids / Q000378:metabolism*; D001665:Binding Sites; D002384:Catalysis; D006801:Humans; D008958:Models, Molecular; D011487:Protein Conformation; D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry / Q000378:metabolism*
D000596:Amino Acids; D011768:Pyruvate Dehydrogenase Complex