Miyakawa Isamu, Kanayama Miwako, Fujita Yuka, Sato Hiroshi
Department of Biology, Faculty of Science, Yamaguchi University, Yamaguchi, Japan.
J Gen Appl Microbiol. 2010;56(6):455-64. doi: 10.2323/jgam.56.455.
To elucidate the role of Abf2p, a major mitochondrial DNA-binding protein in the yeast Saccharomyces cerevisiae, we examined the morphology of the mitochondrial nucleoids (mt-nucleoids) in an ABF2-deficient mutant (Δabf2) in vivo and in vitro by 4',6-diamidino-2-phenylindole (DAPI) staining. The mt-nucleoids appeared as diffuse structures with irregular-size in Δabf2 cells that were grown to log phase in YPG medium containing glycerol, in contrast to the strings-of-beads appearance of mt-nucleoids in wild-type cells. In addition, DAPI-fluorescence intensity of the mt-nucleoids transmitted to the bud was significantly lower in Δabf2 cells than in wild-type cells at log phase. However, the lack of Abf2p did not affect the morphology or segregation of mitochondria. The protein composition of the mt-nucleoids isolated from Δabf2 cells grown to stationary phase in YPG medium was very similar to that of the mt-nucleoids isolated from wild-type cells cultured under the same conditions, except for the lack of Abf2p. These results together suggested that in log-phase cells, the lack of Abf2p influences not only the morphology of mt-nucleoids but also their transmission into the bud. On the other hand, our result suggested that in stationary-phase cells, the lack of Abf2p does not significantly alter the protein composition of the mt-nucleoids.
为阐明酿酒酵母中主要的线粒体DNA结合蛋白Abf2p的作用，我们通过4',6-二脒基-2-苯基吲哚（DAPI）染色在体内和体外检测了ABF2缺陷型突变体（Δabf2）中线粒体类核（mt-类核）的形态。与野生型细胞中呈串珠状的mt-类核不同，在含有甘油的YPG培养基中生长至对数期的Δabf2细胞中，mt-类核呈现出大小不规则的弥散结构。此外，在对数期，Δabf2细胞中传递到芽中的mt-类核的DAPI荧光强度显著低于野生型细胞。然而，缺乏Abf2p并不影响线粒体的形态或分离。从在YPG培养基中生长至稳定期的Δabf2细胞中分离得到的mt-类核的蛋白质组成，除了缺少Abf2p外，与在相同条件下培养的野生型细胞中分离得到的mt-类核非常相似。这些结果共同表明，在对数期细胞中，缺乏Abf2p不仅影响mt-类核的形态，还影响其向芽中的传递。另一方面，我们的结果表明，在稳定期细胞中，缺乏Abf2p不会显著改变mt-类核的蛋白质组成。
