Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia; Faculty of Biology and Biotechnologies, National Research University Higher School of Economics, ul. Vavilova, 7, Moscow, 117312, Russia.
Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie gory 1/40, Moscow, 119991, Russia.
Biochem Biophys Res Commun. 2021 Apr 9;548:74-77. doi: 10.1016/j.bbrc.2021.02.023. Epub 2021 Feb 23.
Peroxidase activity of cytochrome c (cyt c)/cardiolipin (CL) complex is supposed to be involved in the initiation of apoptosis via peroxidative induction of mitochondrial membrane permeabilization. As cyt c binding to CL-containing membranes is at least partially associated with electrostatic protein/lipid interaction, we screened single-point mutants of horse heart cyt c with various substitutions of lysine at position 72, considered to play a significant role in both the binding and peroxidase activity of the protein. Contrary to expectations, K72A, K72R and K72L substitutions exerted slight effects on both the cyt c binding to CL-containing liposomal membranes and the cyt c/HO-induced calcein leakage from liposomes, used here as a membrane permeabilization assay. Both the binding and permeabilization were decreased to various extents, but not significantly, in the case of K72E and K72N mutants. A drastic difference was found between the sequence of the permeabilizing activities of the cyt c variants and the previously described order of their proapoptotic activities (Chertkova et al., 2008).
细胞色素 c（cyt c）/心磷脂（CL）复合物的过氧化物酶活性被认为通过过氧化物诱导线粒体膜通透性的增加而参与细胞凋亡的起始。由于 cyt c 与含有 CL 的膜的结合至少部分与静电蛋白/脂质相互作用有关，我们筛选了马心 cyt c 的单点突变体，这些突变体在位置 72 处具有各种赖氨酸取代，被认为在蛋白的结合和过氧化物酶活性中都起着重要作用。出乎意料的是，K72A、K72R 和 K72L 取代对 cyt c 与含有 CL 的脂质体膜的结合以及 cyt c/HO 诱导的 calcein 从脂质体中的渗漏几乎没有影响，这里用作膜通透性测定。在 K72E 和 K72N 突变体的情况下，结合和通透性都在不同程度上降低，但没有显著降低。细胞色素 c 变体的通透性活性的序列与先前描述的它们的促凋亡活性的顺序（Chertkova 等人，2008）之间存在明显差异。
