Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Science. 2012 Sep 14;337(6100):1333-6. doi: 10.1126/science.1222597.
A specifically patterned cell wall is a determinant of plant cell shape. Yet, the precise mechanisms that underlie initiation of cell wall patterning remain elusive. By using a reconstitution assay, we revealed that ROPGEF4 (Rho of plant guanine nucleotide exchange factor 4) and ROPGAP3 [ROP guanosine triphosphatase (GTPase)-activating protein 3] mediate local activation of the plant Rho GTPase ROP11 to initiate distinct pattern of secondary cell walls in xylem cells. The activated ROP11 recruits MIDD1 to induce local disassembly of cortical microtubules. Conversely, cortical microtubules eliminate active ROP11 from the plasma membrane through MIDD1. Such a mutual inhibitory interaction between active ROP domains and cortical microtubules establishes the distinct pattern of secondary cell walls. This Rho-based regulatory mechanism shows how plant cells initiate and control cell wall patterns to form various cell shapes.
特定模式的细胞壁是植物细胞形状的决定因素。然而，细胞壁模式形成的基础的确切机制仍难以捉摸。通过使用重组测定法，我们揭示了 ROPGEF4（植物鸟嘌呤核苷酸交换因子 4）和 ROPGAP3[ROP 鸟嘌呤核苷酸三磷酸酶（GTPase）-激活蛋白 3]介导植物 Rho GTPase ROP11 的局部激活，从而在木质部细胞中启动次生细胞壁的独特模式。激活的 ROP11 招募 MIDD1 诱导皮质微管的局部解体。相反，皮质微管通过 MIDD1 将活性 ROP11 从质膜中去除。活性 ROP 结构域和皮质微管之间的这种相互抑制相互作用建立了次生细胞壁的独特模式。这种基于 Rho 的调节机制展示了植物细胞如何启动和控制细胞壁模式形成各种细胞形状。
