Institute of Structural Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich, Germany.
J Cell Biol. 2010 May 3;189(3):497-510. doi: 10.1083/jcb.201002076.
Type V myosin (MyoV)-dependent transport of cargo is an essential process in eukaryotes. Studies on yeast and vertebrate MyoV showed that their globular tails mediate binding to the cargo complexes. In Saccharomyces cerevisiae, the MyoV motor Myo4p interacts with She3p to localize asymmetric synthesis of HO 1 (ASH1) mRNA into the bud of dividing cells. A recent study showed that localization of GFP-MS2-tethered ASH1 particles does not require the Myo4p globular tail, challenging the supposed role of this domain. We assessed ASH1 mRNA and Myo4p distribution more directly and found that their localization is impaired in cells expressing globular tail-lacking Myo4p. In vitro studies further show that the globular tail together with a more N-terminal linker region is required for efficient She3p binding. We also determined the x-ray structure of the Myo4p globular tail and identify a conserved surface patch important for She3p binding. The structure shows pronounced similarities to membrane-tethering complexes and indicates that Myo4p may not undergo auto-inhibition of its motor domain.
V 型肌球蛋白（MyoV）依赖的货物运输是真核生物中的一个基本过程。对酵母和脊椎动物 MyoV 的研究表明，它们的球状尾部介导与货物复合物的结合。在酿酒酵母中，MyoV 马达 Myo4p 与 She3p 相互作用，将 HO 1（ASH1）mRNA 的不对称合成定位到正在分裂的细胞的芽中。最近的一项研究表明，GFP-MS2 连接的 ASH1 颗粒的定位不需要 Myo4p 球状尾部，这对该结构域的假定作用提出了挑战。我们更直接地评估了 ASH1 mRNA 和 Myo4p 的分布，发现表达缺乏球状尾部的 Myo4p 的细胞中其定位受到损害。体外研究进一步表明，球状尾部和更 N 端的连接区对于 She3p 的有效结合是必需的。我们还确定了 Myo4p 球状尾部的 X 射线结构，并确定了一个对 She3p 结合很重要的保守表面斑块。该结构显示出与膜连接复合物的显著相似性，并表明 Myo4p 可能不会对其马达结构域进行自动抑制。
