Xie Q, Sanz-Burgos A P, Guo H, García J A, Gutiérrez C
Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autónoma, Madrid, Spain.
Plant Mol Biol. 1999 Mar;39(4):647-56. doi: 10.1023/a:1006138221874.
Geminiviruses encode a few proteins and depend on cellular factors to complete their replicative cycle. As a way to understand geminivirus-host interactions, we have searched for cellular proteins which interact with viral proteins. By using the yeast two-hybrid technology and the wheat dwarf geminivirus (WDV) RepA protein as a bait, we have isolated a family of proteins which we termed GRAB (for Geminivirus Rep A-binding). We report here the molecular characterization of two members, GRAB1 and GRAB2. We have found that the 37 C-terminal amino acids of RepA are required for interaction with GRAB proteins. This region contains residues conserved in an equivalent region of the RepA proteins encoded by other viruses of the WDV subgroup. The N-terminal domain of GRAB proteins is necessary and sufficient to interact with WDV RepA. GRAB proteins contain an unique acidic C-terminal domain while their N-terminal domain, of ca. 170 amino acids, are highly conserved in all of them. Interestingly, this conserved N-terminal domain of GRAB proteins exhibits a significant amino acid homology to the NAC domain present in proteins involved in plant development and senescence. GRAB1 and GRAB2 mRNAs are present in cultured cells and roots but are barely detectable in leaves. GRAB expression inhibits WDV DNA replication in cultured wheat cells. Our studies highlight the importance that the pathway(s) mediated by GRAB proteins, as well as by other NAC domain-containing proteins, might have on geminivirus DNA replication in connection to plant growth, development and senescence pathways.
双生病毒编码少数几种蛋白质，并依赖细胞因子来完成其复制周期。作为理解双生病毒与宿主相互作用的一种方式，我们寻找了与病毒蛋白相互作用的细胞蛋白。通过使用酵母双杂交技术，并以小麦矮缩双生病毒（WDV）的RepA蛋白作为诱饵，我们分离出了一类蛋白质，我们将其命名为GRAB（双生病毒Rep A结合蛋白）。我们在此报告GRAB1和GRAB2这两个成员的分子特征。我们发现RepA的37个C末端氨基酸对于与GRAB蛋白的相互作用是必需的。该区域包含在WDV亚组其他病毒编码的RepA蛋白的等效区域中保守的残基。GRAB蛋白的N末端结构域对于与WDV RepA相互作用是必要且充分的。GRAB蛋白含有一个独特的酸性C末端结构域，而它们约170个氨基酸的N末端结构域在所有成员中高度保守。有趣的是，GRAB蛋白的这个保守N末端结构域与参与植物发育和衰老的蛋白质中存在的NAC结构域具有显著的氨基酸同源性。GRAB1和GRAB2的mRNA存在于培养细胞和根中，但在叶中几乎检测不到。GRAB的表达抑制培养的小麦细胞中WDV DNA的复制。我们的研究强调了由GRAB蛋白以及其他含NAC结构域的蛋白介导的途径在与植物生长、发育和衰老途径相关的双生病毒DNA复制中可能具有的重要性。
