Phosphorylation of NtMAP65-1 by a MAP kinase down-regulates its activity of microtubule bundling and stimulates progression of cytokinesis of tobacco cells
Phosphorylation of NtMAP65-1 by a MAP kinase down-regulates its activity of microtubule bundling and stimulates progression of cytokinesis of tobacco cells
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DOI：
10.1101/gad.1408106
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发表时间：
2006-04-15
影响因子：
10.5
通讯作者：
Machida, Y
中科院分区：
文献类型：
--
作者：
Sasabe, M;Soyano, T;Machida, Y
烟草丝裂原活化蛋白激酶（MAPK）级联，其包括MAPK NRK 1/NTF 6，正调节称为成膜体的细胞动力学机制的扩增，其随后是用于完成细胞分裂的细胞板的合成。然而，MAPK和成膜体扩张之间的分子事件是未知的。在这里，我们表明，NRK 1/NTF 6磷酸化的位置579在NtMAP 65 -1a，微管相关（MT相关）蛋白的苏氨酸残基。当NRK 1/NTF 6被激活时，磷酸化NtMAP 65 -1的水平在细胞周期的晚期M期增加。磷酸化的NtMAP 65 -1集中在成膜体的赤道处，NRK 1/NTF 6也是如此。不能被NRK 1磷酸化的NtMAP 65 -1a突变形式的过表达延迟了M期和成膜体扩张的进展，也使得成膜体结构对MT解聚药物具有抗性。NRK 1/NTF 6对NtMAP 65 -1的磷酸化在体外下调其MT捆绑活性。这些结果表明，NtMAP 65 -1的NRK 1/NTF 6磷酸化也降低了其MT-捆绑活性在体内，这增强了不稳定和营业额的MT在成膜体赤道，也许促进成膜体扩张。
The tobacco mitogen-activated protein kinase (MAPK) cascade, which includes MAPK NRK1/NTF6, positively regulates expansion of the cytokinetic machinery known as the phragmoplast, which is followed by the synthesis of cell plates for completion of cell division. However, molecular events lying between the MAPK and phragmoplast expansion were not known. Here, we show that NRK1/NTF6 phosphorylates the threonine residue at position 579 in NtMAP65-1a, a microtubule-associated (MT-associated) protein. Levels of phosphorylated NtMAP65-1 increase during late M phase of the cell cycle, when NRK1/NTF6 is activated. Phosphorylated NtMAP65-1 is concentrated at the equator of phragmoplast, as is NRK1/NTF6. Overexpression of mutant forms of NtMAP65-1a that cannot be phosphorylated by NRK1 delays progression of the M phase and phragmoplast expansion, also rendering phragmoplast structures resistant to an MT-depolymerizing drug. Phosphorylation of NtMAP65-1 by NRK1/NTF6 down-regulates its MT-bundling activity in vitro. These results suggest that phosphorylation of NtMAP65-1 by NRK1/NTF6 also reduces its MT-bundling activity in vivo, which enhances destabilization and turnover of MTs at the phragmoplast equator, perhaps facilitating phragmoplast expansion.