A semidominant mutation in an Arabidopsis mitogen-activated protein kinase phosphatase-like gene compromises cortical microtubule organization
A semidominant mutation in an Arabidopsis mitogen-activated protein kinase phosphatase-like gene compromises cortical microtubule organization
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DOI：
10.1105/tpc.021865
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发表时间：
2004-07-01
期刊：
影响因子：
11.6
通讯作者：
Hashimoto, T
中科院分区：
文献类型：
--
作者：
Naoi, K;Hashimoto, T
可逆的蛋白质磷酸化调节许多细胞过程，包括微管细胞骨架的动力学和组织，但对介导它的事件知之甚少。拟南芥PROPYZAMIDE-HYPERSENSITIVE I基因座的半显性phs 1 -1等位基因表现出指示皮质微管功能受损的表型，例如幼苗根的左旋螺旋生长，在低剂量微管去稳定化药物下的缺陷性各向异性生长，温度敏感性微管组织的增强1 -1表型，与野生型相比，皮层微管阵列的有序性更低，碎片更多。PHS 1编码一种类似于丝裂原活化蛋白激酶（MAPK）磷酸酶的新蛋白。在phs 1 -1，保守的精氨酸残基在非催化N-末端区域与Cys交换，和突变体PHS 1保留相当大的磷酸酶活性在体外。在哺乳动物MAPK磷酸酶中，相应的区域作为MAPK的对接基序，类似的Arg取代严重抑制激酶-磷酸酶缔合。转基因研究表明，phs 1 -1突变的显性负作用，而无效的phs 1 -2等位基因是隐性胚胎致死。我们建议，PHS 1磷酸酶调节一个以上的MAPK和它的靶激酶的一个子集参与组织的皮质微管。
Reversible protein phosphorylation regulates many cellular processes, including the dynamics and organization of the microtubule cytoskeleton, but the events mediating it are poorly understood. A semidominant phs1-1 allele of the Arabidopsis thaliana PROPYZAMIDE-HYPERSENSITIVE I locus exhibits phenotypes indicative of compromised cortical microtubule functions, such as left-handed helical growth of seedling roots, defective anisotropic growth at low doses of microtubule-destabilizing drugs, enhancement of the temperature-sensitive microtubule organization1-1 phenotype, and less ordered and more fragmented cortical microtubule arrays compared with the wild type. PHS1 encodes a novel protein similar to mitogen-activated protein kinase (MAPK) phosphatases. In phs1-1, a conserved Arg residue in the noncatalytic N-terminal region is exchanged with Cys, and the mutant PHS1 retained considerable phosphatase activity in vitro. In mammalian MAPK phosphatases, the corresponding region serves as a docking motif for MAPKs, and analogous Arg substitutions severely inhibit the kinase-phosphatase association. Transgenic studies indicate that the phs1-1 mutation acts dominant negatively, whereas the null phs1-2 allele is recessive embryonic lethal. We propose that the PHS1 phosphatase regulates more than one MAPK and that a subset of its target kinases is involved in the organization of cortical microtubules.