Mooser Daniela, Maneg Oliver, MacMillan Fraser, Malatesta Francesco, Soulimane Tewfik, Ludwig Bernd
Molekulare Genetik, Institut für Biochemie, Biozentrum der J. W. Goethe-Universität, 60439 Frankfurt am Main, Germany.
Biochim Biophys Acta. 2006 Sep-Oct;1757(9-10):1084-95. doi: 10.1016/j.bbabio.2006.05.033. Epub 2006 May 27.
A recently resolved respiratory complex III, isolated from the extreme thermophile Thermus thermophilus, is discussed in terms of cofactor and subunit composition, and with respect to the origin of its protein modules. The four polypeptides, encoded by a single operon, share general homologies to canonical complexes both of the bc and b6f type, but exhibit some unexpected features as well. Evidence for high thermostability of the isolated protein and for its quinol substrate specificity is derived from EPR and kinetic measurements. A functional integration of this complex into an aerobic electron transfer scheme, connecting known dehydrogenase activities to the terminal oxidase branches of Thermus is outlined, as well as the specific principles of redox protein interactions prevailing at high temperature. Findings from this enzyme are linked to present knowledge on other menaquinol oxidizing bc complexes.
本文讨论了一种最近从嗜热栖热菌（Thermus thermophilus）中分离得到的、已解析的呼吸复合物III，内容涉及辅因子和亚基组成，以及其蛋白质模块的起源。由单个操纵子编码的这四种多肽，与bc型和b6f型的典型复合物具有一般同源性，但也表现出一些意想不到的特征。通过电子顺磁共振（EPR）和动力学测量，获得了该分离蛋白具有高热稳定性及其对醌醇底物特异性的证据。概述了该复合物在有氧电子传递体系中的功能整合，即将已知的脱氢酶活性与嗜热栖热菌的末端氧化酶分支相连接，以及高温下氧化还原蛋白相互作用的具体原理。该酶的研究结果与目前关于其他甲萘醌氧化bc复合物的知识相关联。
