Shigeoka Yuichi, Fujisawa Tetsuro, Teshiba Satoshi, Fukumori Hisayoshi, Yamamoto Kohji, Banno Yutaka, Aso Yoichi
Institute of Genetic Resources, Faculty of Agriculture, Kyushu University.
Biosci Biotechnol Biochem. 2013;77(8):1637-44. doi: 10.1271/bbb.130161. Epub 2013 Aug 7.
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.
嗜热栖热放线菌硫辛酸乙酰转移酶（E2）由60个相同亚基组成，是丙酮酸脱氢酶复合体（PDC）的核心成分。E2多肽由LD、PSBD和CD结构域组成。大多数研究聚焦于缺乏LD和PSBD的截短型E2，因为CD主要有助于维持多聚体结构。我们研究了未截短的E2在盐诱导下的变化并构建了反应模型。我们推测，在存在氯化钾的情况下，E2解离成单体，然后组装成聚集复合体（C(A)）和准稳定复合体（C(Q)）。C(A)大于C(Q)，但小于完整的E2。C(A)和C(Q)分别是约中性pH和碱性pH下的主要复合体。PSBD被其他成分占据的PDC和截短型E2仅发生解离。除CD外，LD-PSBD区域可能有助于解离的E2的部分缔合。
