Kurth Elizabeth G, Peremyslov Valera V, Turner Hannah L, Makarova Kira S, Iranzo Jaime, Mekhedov Sergei L, Koonin Eugene V, Dolja Valerian V
Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331.
National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894.
Proc Natl Acad Sci U S A. 2017 Feb 21;114(8):E1385-E1394. doi: 10.1073/pnas.1620577114. Epub 2017 Jan 17.
We investigate the myosin XI-driven transport network in using protein-protein interaction, subcellular localization, gene knockout, and bioinformatics analyses. The two major groups of nodes in this network are myosins XI and their membrane-anchored receptors (MyoB) that, together, drive endomembrane trafficking and cytoplasmic streaming in the plant cells. The network shows high node connectivity and is dominated by generalists, with a smaller fraction of more specialized myosins and receptors. We show that interaction with myosins and association with motile vesicles are common properties of the MyoB family receptors. We identify previously uncharacterized myosin-binding proteins, putative myosin adaptors that belong to two unrelated families, with four members each (MadA and MadB). Surprisingly, MadA1 localizes to the nucleus and is rapidly transported to the cytoplasm, suggesting the existence of myosin XI-driven nucleocytoplasmic trafficking. In contrast, MadA2 and MadA3, as well as MadB1, partition between the cytosolic pools of motile endomembrane vesicles that colocalize with myosin XI-K and diffuse material that does not. Gene knockout analysis shows that MadB1-4 contribute to polarized root hair growth, phenocopying myosins, whereas MadA1-4 are redundant for this process. Phylogenetic analysis reveals congruent evolutionary histories of the myosin XI, MyoB, MadA, and MadB families. All these gene families emerged in green algae and show concurrent expansions via serial duplication in flowering plants. Thus, the myosin XI transport network increased in complexity and robustness concomitantly with the land colonization by flowering plants and, by inference, could have been a major contributor to this process.
我们运用蛋白质-蛋白质相互作用、亚细胞定位、基因敲除和生物信息学分析方法，对肌球蛋白XI驱动的运输网络进行了研究。该网络中的两大主要节点类型是肌球蛋白XI及其膜锚定受体（MyoB），它们共同驱动植物细胞内膜泡运输和细胞质流动。该网络显示出高节点连通性，且以通用型为主，更具特异性的肌球蛋白和受体占比相对较小。我们发现与肌球蛋白相互作用以及与运动性囊泡结合是MyoB家族受体的共同特性。我们鉴定出了此前未被表征的肌球蛋白结合蛋白，即属于两个不相关家族的假定肌球蛋白适配体，每个家族各有四个成员（MadA和MadB）。令人惊讶的是，MadA1定位于细胞核并迅速转运至细胞质，这表明存在肌球蛋白XI驱动的核质运输。相比之下，MadA2和MadA3以及MadB1则分布于与肌球蛋白XI-K共定位的运动内膜泡的胞质池和不共定位的扩散物质之间。基因敲除分析表明，MadB1-4对根毛的极性生长有贡献，其表型与肌球蛋白相似，而MadA1-4在此过程中功能冗余。系统发育分析揭示了肌球蛋白XI、MyoB、MadA和MadB家族一致的进化历史。所有这些基因家族均起源于绿藻，并在开花植物中通过连续重复实现了同步扩张。因此，肌球蛋白XI运输网络的复杂性和稳健性随着开花植物向陆地的定殖而增加，据此推断，它可能是这一过程的主要促成因素。
