Salt-induced changes in the subunit structure of the Bacillus stearothermophilus lipoate acetyltransferase.
The Bacillus stearothermophilus lipoate acetyltransferase (E2), composed of sixty identical, subunits is the core component of the pyruvate dehydrogenase complex (PDC). E2 polypeptide is composed of LD, PSBD, and CD domains. Most studies had focused on a truncated E2 that is deficient in LD and PSBD, because CD mainly contributes to maintaining the multimeric structure. We examined salt-induced changes in E2 without truncation and constructed reaction models. We speculate that in the presence of KCl, E2 is dissociated into a monomer and then assembled into an aggregative complex (C(A)) and a quasi-stable complex (C(Q)). C(A) was larger than C(Q), but smaller than intact E2. C(A) and C(Q), were dominant complexes at about neutral pH and at basic pH respectively. PDC, in which PSBD is occupied by other components, and a truncated E2 undergo dissociation only. LD-PSBD region besides CD might then contribute to the partial association of dissociated E2.
Institute of Genetic Resources, Faculty of Agriculture, Kyushu University.
Yuichi
Y
Shigeoka
Tetsuro
T
Fujisawa
Satoshi
S
Teshiba
Hisayoshi
H
Fukumori
Kohji
K
Yamamoto
Yutaka
Y
Banno
Yoichi
Y
Aso
D051047:Dihydrolipoyllysine-Residue Acetyltransferase / Q000737:chemistry*; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry*; D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry*; D012492:Salts / Q000494:pharmacology
D010455:Peptides; D021122:Protein Subunits; D011768:Pyruvate Dehydrogenase Complex; D012492:Salts; D051047:Dihydrolipoyllysine-Residue Acetyltransferase