Mazur Monika, Wojtkowska Małgorzata, Skalski Marcin, Słocińska Małgorzata, Kmita Hanna
Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland.
Department of Animal Physiology, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland.
Acta Biochim Pol. 2019 Nov 12;66(4):551-557. doi: 10.18388/abp.2019_2791.
Despite its complex life cycle including unicellular and multicellular stages, the slime mold Dictyostelium discoideum, a well-known model in biomedical research, has not been used as a model organism in studies on mitochondrial import, including its significance in cellular processes. Moreover, data concerning mitochondrial protein import machinery in D. discoideum mitochondria is limited and nothing is known about the impact of that machinery on slime mold life cycle. Here, we focused on the TOB/SAM (topogenesis of the mitochondrial outer membrane β-barrel proteins/sorting and assembly machinery) complex. This complex is localized in the mitochondrial outer membrane and is indispensable for the formation of metabolite exchange and protein import pathways in the membrane, and substantially contributes to the regulation of mitochondrial morphology and distribution. Furthermore, the available data suggests that the TOB/SAM complex variants differ between mitochondria of multicellular and unicellular eukaryotes. Therefore, we decided to determine these variants of the TOB/SAM in mitochondria of D. discoideum progressing from single cells to early multicellular stages, when the cells stream together to form a multicellular organism. The results revealed two complex variants of the TOB/SAM complex of about 160 and 600 kDa molecular weight, present in mitochondria of D. discoideum cells at the studied stages. The discussed complex variants resemble the ones that have been already detected for the yeast Saccharomyces cerevisiae, fungus Neurospora crassa and human cells, and one of investigated variants differentiates unicellular and initial multicellular stages of the D. discoideum life cycle.
尽管黏菌盘基网柄菌的生命周期复杂，包括单细胞和多细胞阶段，但它作为生物医学研究中的著名模型，尚未被用作线粒体导入研究的模式生物，包括其在细胞过程中的意义。此外，关于盘基网柄菌线粒体中蛋白质导入机制的数据有限，且对于该机制对黏菌生命周期的影响一无所知。在此，我们聚焦于TOB/SAM（线粒体外膜β-桶状蛋白的拓扑形成/分选与组装机制）复合体。该复合体定位于线粒体外膜，对于膜中代谢物交换和蛋白质导入途径的形成不可或缺，并且对线粒体形态和分布的调节有重要作用。此外，现有数据表明，多细胞和单细胞真核生物线粒体中的TOB/SAM复合体变体存在差异。因此，我们决定确定盘基网柄菌从单细胞到早期多细胞阶段（此时细胞聚集形成多细胞生物体）线粒体中的这些变体。结果显示，在所研究阶段的盘基网柄菌细胞线粒体中存在分子量约为160 kDa和600 kDa的两种TOB/SAM复合体变体。所讨论的复合体变体类似于已在酿酒酵母、粗糙脉孢菌和人类细胞中检测到的变体，并且所研究的变体之一能够区分盘基网柄菌生命周期的单细胞和初始多细胞阶段。
