The helicase domain of the TMV replicase proteins induces the N-mediated defence response in tobacco
The helicase domain of the TMV replicase proteins induces the N-mediated defence response in tobacco
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DOI：
10.1046/j.1365-313x.1999.00426.x
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发表时间：
1999-04-01
期刊：
影响因子：
7.2
通讯作者：
Baker, B
中科院分区：
文献类型：
--
作者：
Erickson, FL;Holzberg, S;Baker, B
烟草花叶病毒（TMV）在含N基因的烟草植株中诱导过敏反应（HR）。这种防御反应的特征是病毒感染部位的细胞死亡和病毒复制和运动的抑制。先前的一项研究表明，含有推测解旋酶结构域的部分IMV复制酶参与了HR诱导。本研究证实并扩展了这一观察结果，证明50 kDa的TMV解旋酶片段（p50）的非病毒表达足以诱导烟草中n介导的HR。与TMV感染引起的HR一样，转基因p50的表达诱导了温度敏感的防御反应。我们证明重组p50蛋白具有atp酶活性，正如在atp酶/解旋酶中发现的保守序列基序所表明的那样。改变这些基序之一的点突变会在体外消除atp酶活性，但不会影响HR诱导。这些结果表明，不依赖于其酶活性的TMV解旋酶结构域的特征被含氮烟草识别，从而诱导TMV抗性。
Tobacco mosaic virus (TMV) induces the hypersensitive response (HR) in tobacco plants containing the N gene. This defence response is characterized by cell death at the site of virus infection and inhibition of viral replication and movement. A previous study indicated that a portion of the IMV replicase containing a putative helicase domain is involved in HR induction. Here, this observation is confirmed and extended by showing that non-viral expression of a 50 kDa TMV helicase fragment (p50) is sufficient to induce the N-mediated HR in tobacco. Like the HR elicited by TMV infection, transgenic expression of p50 induces a temperature-sensitive defence response. We demonstrate that recombinant p50 protein has ATPase activity, as suggested by the presence of conserved sequence motifs found in ATPase/helicase enzymes. A point mutation that alters one of these motifs abolishes ATPase activity in vitro but does not affect HR induction. These results suggest that features of the TMV helicase domain, independent of its enzymatic activity, are recognized by N-containing tobacco to induce TMV resistance.