Mlc1p is a light chain for the unconventional myosin Myo2p in Saccharomyces cerevisiae.
Mlc1p is a light chain for the unconventional myosin Myo2p in Saccharomyces cerevisiae.
复制标题
MLC1P是酿酒酵母中非常规肌球蛋白肌球蛋白肌球蛋白肌球蛋白的轻链。
DOI：
10.1083/jcb.142.3.711
复制
发表时间：
1998-08-10
期刊：
影响因子：
--
通讯作者：
Davis TN
中科院分区：
文献类型：
--
作者：
Stevens RC;Davis TN
在酿酒酵母中，非传统的肌球蛋白Myo2p在极化生长中起着至关重要的作用。我们探讨了颈部区域及其相关轻链在调节Myo2p功能中的作用。令人惊讶的是，我们发现，颈部六个IQ位点的精确缺失导致了一种肌球蛋白Myo2-Δ6IQp，它可以支持酵母菌株以野生型同基因菌株90%的速度生长。我们利用这个突变体来表征Myo2p的轻链。首先，我们证明了钙调蛋白在极化生长部位的定位在很大程度上取决于Myo2p颈部的智商部位。其次，我们证明了一个以前未鉴定的蛋白质Mlc1p是Myo2p的肌球蛋白轻链。MLC1(YGL106w)是一种存在单倍性缺陷的必需基因。MYO2水平的降低克服了MLC1的单倍体不足。突变体myo2-Δ6IQ能够抑制单倍体缺失，但不能抑制缺失。我们使用了一种改进的凝胶覆盖试验来证明Mlc1p和Myo2p的颈部之间有直接的相互作用。MYO2的过度表达是有毒的，导致生长速度严重下降。当MYO2过表达时，Myo2p的稳定性比野生型菌株低四倍。高拷贝的MLC1完全克服了生长缺陷，增加了Myo2p的稳定性。我们的结果表明，Mlc1p通过与颈部结合来稳定这种肌球蛋白。
In Saccharomyces cerevisiae, the unconventional myosin Myo2p is of fundamental importance in polarized growth. We explore the role of the neck region and its associated light chains in regulating Myo2p function. Surprisingly, we find that precise deletion of the six IQ sites in the neck region results in a myosin, Myo2-Δ6IQp, that can support the growth of a yeast strain at 90% the rate of a wild-type isogenic strain. We exploit this mutant in a characterization of the light chains of Myo2p. First, we demonstrate that the localization of calmodulin to sites of polarized growth largely depends on the IQ sites in the neck of Myo2p. Second, we demonstrate that a previously uncharacterized protein, Mlc1p, is a myosin light chain of Myo2p. MLC1 (YGL106w) is an essential gene that exhibits haploinsufficiency. Reduced levels of MYO2 overcome the haploinsufficiency of MLC1. The mutant MYO2-Δ6IQ is able to suppress haploinsufficiency but not deletion of MLC1. We used a modified gel overlay assay to demonstrate a direct interaction between Mlc1p and the neck of Myo2p. Overexpression of MYO2 is toxic, causing a severe decrease in growth rate. When MYO2 is overexpressed, Myo2p is fourfold less stable than in a wild-type strain. High copies of MLC1 completely overcome the growth defects and increase the stability of Myo2p. Our results suggest that Mlc1p is responsible for stabilizing this myosin by binding to the neck region.