Hobbs A E, Srinivasan M, McCaffery J M, Jensen R E
Department of Cell Biology and Anatomy, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
J Cell Biol. 2001 Jan 22;152(2):401-10. doi: 10.1083/jcb.152.2.401.
In the yeast Saccharomyces cerevisiae, mitochondria form a branched, tubular reticulum in the periphery of the cell. Mmm1p is required to maintain normal mitochondrial shape and in mmm1 mutants mitochondria form large, spherical organelles. To further explore Mmm1p function, we examined the localization of a Mmm1p-green fluorescent protein (GFP) fusion in living cells. We found that Mmm1p-GFP is located in small, punctate structures on the mitochondrial outer membrane, adjacent to a subset of matrix-localized mitochondrial DNA nucleoids. We also found that the temperature-sensitive mmm1-1 mutant was defective in transmission of mitochondrial DNA to daughter cells immediately after the shift to restrictive temperature. Normal mitochondrial nucleoid structure also collapsed at the nonpermissive temperature with similar kinetics. Moreover, we found that mitochondrial inner membrane structure is dramatically disorganized in mmm1 disruption strains. We propose that Mmm1p is part of a connection between the mitochondrial outer and inner membranes, anchoring mitochondrial DNA nucleoids in the matrix.
在酿酒酵母中，线粒体在细胞周边形成分支状的管状网络。维持正常线粒体形态需要Mmm1p，在mmm1突变体中，线粒体形成大的球形细胞器。为了进一步探究Mmm1p的功能，我们检测了活细胞中Mmm1p-绿色荧光蛋白（GFP）融合蛋白的定位。我们发现Mmm1p-GFP位于线粒体外膜上的小斑点状结构中，与一部分定位于线粒体基质的线粒体DNA类核相邻。我们还发现，温度敏感型mmm1-1突变体在转移到限制温度后，立即出现线粒体DNA向子细胞传递缺陷。正常的线粒体类核结构在非允许温度下也会以相似的动力学崩溃。此外，我们发现mmm1缺失菌株中线粒体内膜结构严重紊乱。我们提出，Mmm1p是线粒体外膜和内膜之间连接的一部分，将线粒体DNA类核锚定在基质中。
