The functional organization of mitochondrial genomes in human cells
The functional organization of mitochondrial genomes in human cells
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DOI：
10.1186/1741-7007-2-9
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发表时间：
2004-01-01
期刊：
影响因子：
5.4
通讯作者：
Cook, Peter R.
中科院分区：
文献类型：
--
作者：
Iborra, Francisco J.;Kimura, Hiroshi;Cook, Peter R.
背景资料：我们分析了一个稳定的人细胞系（ECV 304，也被称为T-24）中的线粒体DNA的组织和功能，该细胞系含有黄色荧光蛋白标记的线粒体。这些病灶（类核）直接或间接通过线粒体膜与驱动蛋白（标记为KIF 5 B）和周围细胞质中的微管相连。在活细胞中，病灶的表观扩散常数为1.1 × 10 ~（-3）μ m ~（2）/s，线粒体总是在病灶旁边分裂，将所有DNA分配给一个子细胞。复制和转录的动力学（通过掺入溴脱氧尿苷或溴尿苷后的免疫标记监测）揭示了每个基因组在焦点中独立于其他基因组复制，并且新产生的RNA在其产生后很长时间内仍保留在焦点中（停留半衰期类似于43分钟）。这种线粒体RNA与制造和进口核编码蛋白质的细胞质机器的组件共定位-即，核糖体蛋白（S6），新生肽相关蛋白（NAC）和外膜中的易位酶（Tom 22）。结论：结果表明，线粒体基因组簇组织线粒体膜两侧的翻译机器。然后，由核基因组编码并注定要进入线粒体的蛋白质将接近线粒体编码的蛋白质，以便它们可以有效地组装成线粒体复合物。
Background: We analyzed the organization and function of mitochondrial DNA in a stable human cell line (ECV304, which is also known as T-24) containing mitochondria tagged with the yellow fluorescent protein.Results: Mitochondrial DNA is organized in similar to 475 discrete foci containing 6-10 genomes. These foci (nucleoids) are tethered directly or indirectly through mitochondrial membranes to kinesin, marked by KIF5B, and microtubules in the surrounding cytoplasm. In living cells, foci have an apparent diffusion constant of 1.1 x 10(-3) mu m(2)/s, and mitochondria always split next to a focus to distribute all DNA to one daughter. The kinetics of replication and transcription (monitored by immunolabelling after incorporating bromodeoxyuridine or bromouridine) reveal that each genome replicates independently of others in a focus, and that newly-made RNA remains in a focus (residence half-time similar to 43 min) long after it has been made. This mitochondrial RNA colocalizes with components of the cytoplasmic machinery that makes and imports nuclear-encoded proteins - that is, a ribosomal protein (S6), a nascent peptide associated protein (NAC), and the translocase in the outer membrane (Tom22).Conclusions: The results suggest that clusters of mitochondrial genomes organize the translation machineries on both sides of the mitochondrial membranes. Then, proteins encoded by the nuclear genome and destined for the mitochondria will be made close to mitochondrial-encoded proteins so that they can be assembled efficiently into mitochondrial complexes.