Regulation of the myosin-directed chaperone UNC-45 by a novel E3/E4-multiubiquitylation complex in C. elegans
Regulation of the myosin-directed chaperone UNC-45 by a novel E3/E4-multiubiquitylation complex in C. elegans
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DOI：
10.1016/j.cell.2004.07.014
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发表时间：
2004-08-06
期刊：
影响因子：
64.5
通讯作者：
Baumeister, R
中科院分区：
文献类型：
--
作者：
Hoppe, T;Cassata, G;Baumeister, R
将运动蛋白肌球蛋白组织成运动细胞结构需要精确的时间和空间控制。秀丽隐杆线虫 UNC-45 在粗丝组装过程中同时充当肌球蛋白的伴侣和 Hsp90 共伴侣，从而促进了这一过程。因此，线虫 unc45 的突变会导致动物瘫痪，横纹体壁肌肉中肌原纤维严重紊乱。在这里，我们报告了一种新的 E3/E4 复合物，由 CHN-1（CHIP（Hsc70 相互作用蛋白的羧基末端）的线虫直系同源物）和 UFD-2（一种已知在酵母中具有泛素缀合 E4 活性的酶）形成，对于体外多泛素化 UNC-45 是必要且充分的。 unc-45 温度敏感动物的表型因 chn-1 功能丧失而部分受到抑制，而 unc-45 在缺乏 chn-1 的线虫中过度表达会导致肌肉细胞严重混乱。这些结果将 CHN-1 和 UFD-2 确定为功能性 E3/E4 复合物，并将 UNC-45 确定为其生理相关底物。
The organization of the motor protein myosin into motile cellular structures requires precise temporal and spatial control. Caenorhabditis elegans UNC-45 facilitates this by functioning both as a chaperone and as a Hsp90 cochaperone for myosin during thick filament assembly. Consequently, mutations in C. elegans unc45 result in paralyzed animals with severe myofibril disorganization in striated body wall muscles. Here, we report a new E3/E4 complex, formed by CHN-1, the C. elegans ortholog of CHIP (carboxyl terminus of Hsc70-interacting protein), and UFD-2, an enzyme known to have ubiquitin conjugating E4 activity in yeast, as necessary and sufficient to multiubiquitylate UNC-45 in vitro. The phenotype of unc-45 temperature-sensitive animals is partially suppressed by chn-1 loss of function, while UNC-45 overexpression in worms deficient for chn-1 results in severely disorganized muscle cells. These results identify CHN-1 and UFD-2 as a functional E3/E4 complex and UNC-45 as its physiologically relevant substrate.