Li Hua, Zeng Xian, Liu Zi-Qiang, Meng Qiu-Tao, Yuan Ming, Mao Tong-Lin
Department of Plant Sciences, China Agricultural University, Beijing, 100193, China.
Plant Mol Biol. 2009 Feb;69(3):313-24. doi: 10.1007/s11103-008-9426-1. Epub 2008 Nov 11.
Nine genes that encode proteins of the MAP65 family have been identified in the Arabidopsis thaliana genome. In this study, we reported that AtMAP65-2, a member of the AtMAP65 family, could strongly stabilize microtubules (MTs). Bacterially-expressed AtMAP65-2 fusion proteins induced the formation of large MT bundles in vitro. Although AtMAP65-2 showed little effect on MT assembly or nucleation, AtMAP65-2 greatly stabilized MTs that were subjected to low-temperature treatment in vitro. Analyses of truncated versions of AtMAP65-2 indicated that the region that encompassed amino acids 495-578, which formed a flexible extended loop, played a crucial role in the stabilization of MTs. Analysis of suspension-cultured Arabidopsis cells that expressed the AtMAP65-2-GFP fusion protein showed that AtMAP65-2 co-localized with MTs throughout the cell cycle. Cortical MTs that were decorated with AtMAP65-2-GFP were more resistant to the MT-disrupting drug propyzamide and to ice treatment in vivo. The results of this study demonstrate that AtMAP65-2 strongly stabilizes MTs and is involved in the regulation of MT organization and dynamics.
在拟南芥基因组中已鉴定出九个编码微管相关蛋白65（MAP65）家族蛋白的基因。在本研究中，我们报道了AtMAP65家族成员AtMAP65-2能够强烈稳定微管（MTs）。细菌表达的AtMAP65-2融合蛋白在体外诱导形成大型微管束。虽然AtMAP65-2对微管组装或成核影响不大，但AtMAP65-2能极大地稳定体外经受低温处理的微管。对AtMAP65-2截短版本的分析表明，包含氨基酸495 - 578的区域形成了一个柔性延伸环，在微管稳定中起关键作用。对表达AtMAP65-2-GFP融合蛋白的悬浮培养拟南芥细胞的分析表明，AtMAP65-2在整个细胞周期中都与微管共定位。用AtMAP65-2-GFP标记的皮层微管在体内对微管破坏药物丙炔酰胺和冰冻处理更具抗性。本研究结果表明，AtMAP65-2能强烈稳定微管，并参与微管组织和动态的调控。
