Loss of cargo binding in the human myosin VI deafness mutant (R1166X) leads to increased actin filament binding.
Loss of cargo binding in the human myosin VI deafness mutant (R1166X) leads to increased actin filament binding.
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DOI：
10.1042/bcj20160571
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发表时间：
2016-10-01
期刊：
影响因子：
--
通讯作者：
Buss F
中科院分区：
文献类型：
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作者：
Arden SD;Tumbarello DA;Butt T;Kendrick-Jones J;Buss F
肌球蛋白VI的突变与人类常染色体隐性（DFNB 37）和常染色体显性（DFNA 22）耳聋相关。在这里，我们发现了一个肌球蛋白VI无义突变（R1166 X），该突变在巴基斯坦的一个遗传性听力损失家族中被发现。该突变导致肌球蛋白VI货物结合结构域的C-末端120个氨基酸的缺失，其包括衔接蛋白LMTK 2、Tom 1以及Dab 2的WWY结合基序。有趣的是，通过表达具有R1166 X突变或在接头结合位点具有单点突变的肌球蛋白VI来损害肌球蛋白VI囊泡结合能力，导致该肌球蛋白在体外和体内的F-肌动蛋白结合增加。由于我们的研究结果突出了货物附件调节肌动蛋白结合到马达结构域的重要性，我们进行了详细的表征衔接蛋白结合，并确定单个氨基酸内肌球蛋白VI结合货物衔接所需的。我们不仅表明衔接蛋白可以直接与肌球蛋白VI的货物结合尾相互作用，而且我们的体外研究还表明，多个衔接蛋白可以同时结合到肌球蛋白VI尾中的非重叠位点。总之，我们对人肌球蛋白VI耳聋突变体（R1166 X）的表征表明，货物结合缺陷可能使肌球蛋白VI处于引发/激活状态，具有增加的肌动蛋白结合能力。
Mutations in myosin VI have been associated with autosomal-recessive (DFNB37) and autosomal-dominant (DFNA22) deafness in humans. Here, we characterise an myosin VI nonsense mutation (R1166X) that was identified in a family with hereditary hearing loss in Pakistan. This mutation leads to the deletion of the C-terminal 120 amino acids of the myosin VI cargo-binding domain, which includes the WWY-binding motif for the adaptor proteins LMTK2, Tom1 as well as Dab2. Interestingly, compromising myosin VI vesicle-binding ability by expressing myosin VI with the R1166X mutation or with single point mutations in the adaptor-binding sites leads to increased F-actin binding of this myosin in vitro and in vivo. As our results highlight the importance of cargo attachment for regulating actin binding to the motor domain, we perform a detailed characterisation of adaptor protein binding and identify single amino acids within myosin VI required for binding to cargo adaptors. We not only show that the adaptor proteins can directly interact with the cargo-binding tail of myosin VI, but our in vitro studies also suggest that multiple adaptor proteins can bind simultaneously to non-overlapping sites in the myosin VI tail. In conclusion, our characterisation of the human myosin VI deafness mutant (R1166X) suggests that defects in cargo binding may leave myosin VI in a primed/activated state with an increased actin-binding ability.