The Endocytosis of Cellulose Synthase in Arabidopsis Is Dependent on μ2, a Clathrin-Mediated Endocytosis Adaptin
The Endocytosis of Cellulose Synthase in Arabidopsis Is Dependent on μ2, a Clathrin-Mediated Endocytosis Adaptin
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DOI：
10.1104/pp.113.221234
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发表时间：
2013-09-01
期刊：
影响因子：
7.4
通讯作者：
Gu, Ying
中科院分区：
文献类型：
--
作者：
Bashline, Logan;Li, Shundai;Gu, Ying
网格蛋白介导的内吞作用（CME）是真核细胞中最具特征的内吞作用类型。植物似乎拥有进行CME所需的所有分子组分;然而，组分的功能表征仍处于起步阶段。酵母双杂交筛选鉴定mu 2为纤维素合成酶6（CESA 6）的推定相互作用伴侣。拟南芥（Arabidopsis thaliana）mu 2与哺乳动物衔接蛋白复合物2（AP 2）的中亚基2同源。在哺乳动物中，AP 2复合物作为CME的中心枢纽，通过与质膜对接，同时将货物蛋白、网格蛋白和辅助蛋白募集到内吞作用的位点。我们证实了mu 2通过mu 2的mu同源结构域与多种CESA蛋白相互作用，mu 2的mu同源结构域参与与哺乳动物中的内吞货物蛋白的特异性相互作用。与其在介导质膜上的货物内吞作用中的作用一致，mu 2-黄色荧光蛋白定位于质膜上的瞬时病灶，mu 2的丢失导致大量内吞作用的缺陷。此外，mu 2的丢失导致质膜上黄色荧光蛋白-CESA 6颗粒的积累增加。我们的研究结果表明，CESA代表了一类新的CME货物蛋白，植物细胞可能通过控制质膜上活性CESA复合物的丰度来调节纤维素合成。
Clathrin-mediated endocytosis (CME) is the best-characterized type of endocytosis in eukaryotic cells. Plants appear to possess all of the molecular components necessary to carry out CME; however, functional characterization of the components is still in its infancy. A yeast two-hybrid screen identified mu 2 as a putative interaction partner of CELLULOSE SYNTHASE6 (CESA6). Arabidopsis (Arabidopsis thaliana) mu 2 is homologous to the medium subunit 2 of the mammalian ADAPTOR PROTEIN COMPLEX2 (AP2). In mammals, the AP2 complex acts as the central hub of CME by docking to the plasma membrane while concomitantly recruiting cargo proteins, clathrin triskelia, and accessory proteins to the sites of endocytosis. We confirmed that mu 2 interacts with multiple CESA proteins through the mu-homology domain of mu 2, which is involved in specific interactions with endocytic cargo proteins in mammals. Consistent with its role in mediating the endocytosis of cargos at the plasma membrane, mu 2-YELLOW FLUORESCENT PROTEIN localized to transient foci at the plasma membrane, and loss of mu 2 resulted in defects in bulk endocytosis. Furthermore, loss of mu 2 led to increased accumulation of YELLOW FLUORESCENT PROTEIN-CESA6 particles at the plasma membrane. Our results suggest that CESA represents a new class of CME cargo proteins and that plant cells might regulate cellulose synthesis by controlling the abundance of active CESA complexes at the plasma membrane through CME.