Boldogh Istvan R, Ramcharan Sharmilee L, Yang Hyeong-Cheol, Pon Liza A
Department of Anatomy and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Mol Biol Cell. 2004 Sep;15(9):3994-4002. doi: 10.1091/mbc.e04-01-0053. Epub 2004 Jun 23.
Two actin-dependent force generators contribute to mitochondrial inheritance: Arp2/3 complex and the myosin V Myo2p (together with its Rab-like binding partner Ypt11p). We found that deletion of YPT11, reduction of the length of the Myo2p lever arm (myo2-Delta6IQ), or deletion of MYO4 (the other yeast myosin V), had no effect on mitochondrial morphology, colocalization of mitochondria with actin cables, or the velocity of bud-directed mitochondrial movement. In contrast, retention of mitochondria in the bud was compromised in YPT11 and MYO2 mutants. Retention of mitochondria in the bud tip of wild-type cells results in a 60% decrease in mitochondrial movement in buds compared with mother cells. In ypt11Delta mutants, however, the level of mitochondrial motility in buds was similar to that observed in mother cells. Moreover, the myo2-66 mutant, which carries a temperature-sensitive mutation in the Myo2p motor domain, exhibited a 55% decrease in accumulation of mitochondria in the bud tip, and an increase in accumulation of mitochondria at the retention site in the mother cell after shift to restrictive temperatures. Finally, destabilization of actin cables and the resulting delocalization of Myo2p from the bud tip had no significant effect on the accumulation of mitochondria in the bud tip.
肌动蛋白相关蛋白2/3复合体（Arp2/3 complex）和肌球蛋白V Myo2p（及其Rab样结合伴侣Ypt11p）。我们发现，缺失YPT11、缩短Myo2p杠杆臂的长度（myo2-Δ6IQ）或缺失MYO4（另一种酵母肌球蛋白V），对线粒体形态、线粒体与肌动蛋白电缆的共定位或芽向线粒体移动的速度均无影响。相反，YPT11和MYO2突变体中芽内线粒体的保留受到损害。与母细胞相比，野生型细胞芽尖中线粒体的保留导致芽中线粒体移动减少60%。然而，在ypt11Δ突变体中，芽中线粒体的运动水平与母细胞中观察到的相似。此外，在Myo2p运动结构域携带温度敏感突变的myo2-66突变体，在转移到限制温度后，芽尖中线粒体的积累减少55%，母细胞中保留位点处线粒体的积累增加。最后，肌动蛋白电缆的不稳定以及由此导致的Myo2p从芽尖的异位对芽尖中线粒体的积累没有显著影响。
