A multilayered regulatory mechanism for the autoinhibition and activation of a plant CC-NB-LRR resistance protein with an extra N-terminal domain
A multilayered regulatory mechanism for the autoinhibition and activation of a plant CC-NB-LRR resistance protein with an extra N-terminal domain
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用于具有额外 N 末端结构域的植物 CC-NB-LRR 抗性蛋白的自动抑制和激活的多层调节机制。
DOI：
10.1111/nph.14013
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发表时间：
2016-10-01
期刊：
影响因子：
9.4
通讯作者：
Tao, Xiaorong
中科院分区：
文献类型：
--
作者：
Chen, Xiaojiao;Zhu, Min;Tao, Xiaorong
番茄抗性蛋白Sw-5 b与经典的卷曲螺旋核苷酸结合富含亮氨酸重复序列（CC-NB-LRR）抗性蛋白的不同之处在于具有额外的N-末端结构域（NTD）。为了了解NTD、CC和NB-LRR如何调节Sw-5 b的自抑制和激活，我们剖析了每个结构域的功能。当病毒诱导子缺失时，Sw-5 b LRR抑制中枢NB-ARC，维持NB-LRR段的自抑制。CC和NTD结构域独立地和加和地增强NB-LRR的自抑制。当病毒诱导子存在时，Sw-5 b的NB-LRR片段被特异性激活以触发过敏反应。令人惊讶的是，Sw-5 b CC抑制NB-LRR的激活，而Sw-5 b的额外NTD成为正调节剂，并完全激活抗性蛋白，可能是通过减轻CC的抑制作用。在转基因植株的感染试验中，单独的NB-LRR片段不足以赋予对番茄斑萎番茄斑萎病毒的抗性; NB-LRR上的NTD和CC调控层需要Sw-5 b赋予抗性。基于这些发现，我们提出，为了对抗CC对NB-LRR的负调节，Sw-5 b进化出额外的NTD来与CC协调，从而开发了一种多层调节机制来控制自身抑制和激活。
The tomato resistance protein Sw-5b differs from the classical coiled-coil nucleotide-binding leucine-rich repeat (CC-NB-LRR) resistance proteins by having an extra N-terminal domain (NTD). To understand how NTD, CC and NB-LRR regulate autoinhibition and activation of Sw-5b, we dissected the function(s) of each domain. When viral elicitor was absent, Sw-5b LRR suppressed the central NB-ARC to maintain autoinhibition of the NB-LRR segment. The CC and NTD domains independently and additively enhanced the autoinhibition of NB-LRR. When viral elicitor was present, the NB-LRR segment of Sw-5b was specifically activated to trigger a hypersensitive response. Surprisingly, Sw-5b CC suppressed the activation of NB-LRR, whereas the extra NTD of Sw-5b became a positive regulator and fully activated the resistance protein, probably by relieving the inhibitory effects of the CC. In infection assays of transgenic plants, the NB-LRR segment alone was insufficient to confer resistance against Tomato spotted wilt tospovirus; the layers of NTD and CC regulation on NB-LRR were required for Sw-5b to confer resistance. Based on these findings, we propose that, to counter the negative regulation of the CC on NB-LRR, Sw-5b evolved an extra NTD to coordinate with the CC, thus developing a multilayered regulatory mechanism to control autoinhibition and activation.