Nuclear localization signal binding protein from Arabidopsis mediates nuclear import of Agrobacterium VirD2 protein
Nuclear localization signal binding protein from Arabidopsis mediates nuclear import of Agrobacterium VirD2 protein
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DOI：
10.1073/pnas.94.20.10723
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发表时间：
1997-09-30
影响因子：
11.1
通讯作者：
Citovsky, V
中科院分区：
文献类型：
--
作者：
Ballas, N;Citovsky, V
T-DNA核输入是农杆菌介导的植物细胞遗传转化中的中心事件。据推测，T-DNA转运中间体是与两种细菌蛋白质VirD 2和VirE 2相关的单链DNA分子，这两种蛋白质最可能介导转运过程。当VirE 2协同包裹转运的单链DNA时，VirD 2共价连接到其5'端，为了更好地理解VirD 2的作用机制，从拟南芥中鉴定了VirD 2的细胞受体并克隆了其编码基因。所鉴定的蛋白质，命名为AtKAP α，在体内和体外特异性结合VirD 2。VirD 2-AtKAP α相互作用完全依赖于VirD 2的羧基端二分核定位信号序列。At-KAP α的氨基酸序列与属于核转运蛋白α家族的酵母和动物核定位信号结合蛋白同源。事实上，AtKAP α有效地拯救了核输入缺陷的酵母突变体。此外，AtKAP α特异性地介导VirD 2转运到透化酵母细胞的核中。
T-DNA nuclear import is a central event in genetic transformation of plant cells by Agrobacterium, Presumably, the T-DNA transport intermediate is a single-stranded DNA molecule associated with two bacterial proteins, VirD2 and VirE2, which most likely mediate the transport process, While VirE2 cooperatively coats the transported single-stranded DNA, VirD2 is covalently attached to its 5' end, To better understand the mechanism of VirD2 action, a cellular receptor for VirD2 was identified and its encoding gene cloned from Arabidopsis. The identified protein, designated AtKAP alpha, specifically bound VirD2 in vivo and in vitro. VirD2-AtKAP alpha interaction was absolutely dependent on the carboxyl-terminal bipartite nuclear localization signal sequence of VirD2. The deduced amino acid sequence of At-KAP alpha was homologous to yeast and animal nuclear localization signal-binding proteins belonging to the karyopherin alpha family, Indeed, AtKAP alpha efficiently rescued a yeast mutant defective for nuclear import, Furthermore, AtKAP alpha specifically mediated transport of VirD2 into the nuclei of permeabilized yeast cells.