Dynamics of packaging and division of the yeast mitochondrial nuclei.

从形态学和生化的角度研究了酵母线粒体核（mt- nucleus）的包装和分裂机制。研究了酿酒酵母由厌氧培养向好氧培养过渡过程中mt-细胞核的动态变化。在培养的过渡过程中，mt-细胞核在6小时内从巨大的聚集体变为小颗粒。在本研究中，我们测定了单个巨型mt-细胞核和小mt-细胞核的DNA含量。接下来，我们发现在厌氧条件下生长的细胞中，两种mt-细胞核蛋白在大mt-细胞核中几乎检测不到，但在转移到有氧条件下，两种蛋白都出现在小mt-细胞核中。利用免疫荧光显微镜，我们发现线粒体的动态形态变化与线粒体核的变化是平行的，细胞质中的肌动蛋白斑块也从聚集形式转变为小斑块，以响应有氧条件。研究了蛋白质组分在mt-细胞核包装中的作用，得到了以下结果。我们鉴定了一种新的mt-细胞核蛋白，命名为Mnp1p。该蛋白是一个22 kda的酸性蛋白，与大肠杆菌核糖体蛋白L7/L12同源。为了从进化角度研究mt-细胞核蛋白的多样性，我们从酵母菌假丝酵母（Candida parapsilosis）中分离了mt-细胞核，并鉴定了几个mt-细胞核蛋白。此外，我们纯化了一个新的30 kda的dna结合蛋白，一个假定的Abf2p同源物。我们还成功地从酵母毕赤酵母中纯化了一个26kda的abf2b样蛋白。比较野生型细胞和abf2p缺陷细胞的mt-细胞核对核酸酶的敏感性。我们发现来自abf2p缺陷细胞的mt-细胞核比来自野生型细胞的mt-细胞核更能抵抗微球菌核酸酶的消化。在研究过程中，我们证明了与mt-细胞核相关的主要核酸酶是Nuc1p核酸酶。被包装成mt核的MtDNA被微球菌核酸酶均匀地而不是不连续地消化。少

Morphological and biochemical approaches were performed on the mechanisms of packaging and division of yeast mitochondrial nuclei (mt-nuclei).1. Dynamic changes in mt-nuclei during the transition from anaerobic to aerobic culture were investigated in the yeast Saccharomyces cerevisiae. During transition of the culture, the mt-nuclei changes their morphology from giant aggregates to small particles within 6 h. In the present study, we determined DNA content of individual giant mt-nuclei and small mt-nuclei. Next, we found that two species of mt-nuclei proteins were hardly detected in giant mt-nuclei in anaerobically-grown cells, but both proteins appeared in the small mt-nuclei during transfer to aerobic conditions. Using immnofluorescence microscopy, we demonstrated that the dynamic morphological changes in mitochondria occur parallel to the changes of the mt-nuclei and that the actin patches in the cytoplasm also changes from the aggregated forms to the small patches in response to th … More e aerobic conditions.2. Roles of protein components on packaging of the mt-nuclei were investigated, and following results were obtained.We identified a novel mt-nuclei protein named as Mnp1p. This protein was a 22-kDa acidic protein and had a homology with E. coli ribosomal protein, L7/L12. In order to examine the diversity of the mt-nuclei proteins from evolutionary aspects, we isolated the mt-nuclei from the yeast Candida parapsilosis and identified several mt-nuclei proteins. Furthermore, we purified a novel 30-kDa DNA-binding protein, a putative Abf2p homolog. We also successfully purified a 26-kDa Abf2p-like protein from the yeast Pichia jadinii.3. Nuclease sensitivity of the mt-nuclei was compared between mt-nuclei from wild-type cells and Abf2p-deficient cells. We found that the mt-nuclei from Abf2p-deficient cells were more resistant to micrococcal nuclease digestion than the mt-nuclei from wild type cells. During the course of study, we demonstrated that a major nuclease associated with mt-nuclei is a Nuc1p nuclease. MtDNA that is packaged into the mt-nuclei was digested uniformly rather than discontinuously with micrococcal nuclease. Less