Structure-function analysis of the tobacco mosaic virus resistance gene N
Structure-function analysis of the tobacco mosaic virus resistance gene N
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DOI：
10.1073/pnas.97.26.14789
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发表时间：
2000-12-19
影响因子：
11.1
通讯作者：
Baker, BJ
中科院分区：
文献类型：
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作者：
Dinesh-Kumar, SP;Tham, WH;Baker, BJ
烟草IV基因是Toll-IL-1受体/核苷酸结合位点/亮氨酸富含重复序列(TIR-NBS-LRR)类植物抗病基因的一员，具有对烟草花叶病毒(TMV)的抗性。我们通过在体内检测引入单一氨基酸替换突变体的各种IV缺失和点突变，研究了N的特定结构域在诱导TMV抗性中的重要性。我们的缺失分析表明，TIR、NBS和LRR结构域在诱导对TMV的抗性反应中起着不可或缺的作用。我们发现，Toll/IL-1R/植物R基因TIR结构域和含NBS蛋白之间的保守氨基酸在N介导的TMV抗性中起着关键作用。一些功能缺失的N等位基因，如NBS(G216A/E/V/R、G218R、G219D、K222E/N和T223A/N)的TIR缺失和点突变，干扰了野生型N的功能，表现为显性负突变。这些F1植株的超敏反应(HR)与野生型N植株几乎没有区别，但TMV能够系统地运动，引起系统超敏反应(SHR)。HI的TIR、NBS和LRR结构域上的许多氨基酸替换导致了部分功能丧失的表型。与野生型N株相比，这些突变体植株安装延迟的HR，并且不能将病毒携带到感染部位。此外，部分功能缺失等位基因(W82S/A、W141S/A、G218V/S和G219V)干扰野生型N功能，导致自发性高血压。本报告中描述的部分功能丧失和显性负突变等位基因将有助于我们进一步了解TIR-NBS-LRR类R基因。
The tobacco IV gene is a member of the Toll-interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat (TIR-NBS-LRR) class of plant resistance (R) genes and confers resistance to tobacco mosaic virus (TMV). We investigated the importance of specific domains of N in inducing TMV resistance, by examining Various IV deletion and point mutations that introduce single amino acid substitution mutants in vivo. Our deletion analysis suggests that the TIR, NBS, and LRR domains play an indispensable role in the induction of resistance responses against TMV. We show that amino acids conserved among the Toll/IL-1R/plant R gene TIR domain and NBS-containing proteins play a critical role in N-mediated TMV resistance. Some loss-of-function N alleles such as the TIR deletion and point mutations in the NBS (G216A/E/V/R, G218R, G219D, K222E/N, and T223A/N) interfere with the wildtype N function and behave like dominant negative mutations. These Fl plants mount a hypersensitive response (HR) that is indistinguishable from that of the wild-type N plants, yet TMV was able to move systemically, causing a systemic hypersensitive response (SHR). Many amino acid substitutions in the TIR, NBS, and LRR domains of hi lead to a partial loss-of-function phenotype. These mutant plants mount delayed HR compared with the wildtype N plants and fail to contain the virus to the infection site. In addition, some partial loss-of-function alleles (W82S/A, W141S/A, G218V/S, and G219V) interfere with the wild-type N function, leading to SHR. The partial loss-of-function and dominant negative mutant alleles described in this report will be useful in furthering our understanding of the TIR-NBS-LRR class of R genes.