title: A multilayered regulatory mechanism for the autoinhibition and activation of a plant CC-NB-LRR resistance protein with an extra N-terminal domain.
abstract: 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.
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Xiaojiao
authors: X
authors: Chen
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Min
authors: M
authors: Zhu
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Lei
authors: L
authors: Jiang
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Wenyang
authors: W
authors: Zhao
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Jia
authors: J
authors: Li
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Jianyan
authors: J
authors: Wu
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Chun
authors: C
authors: Li
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Baohui
authors: B
authors: Bai
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Gang
authors: G
authors: Lu
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Hongyu
authors: H
authors: Chen
authors: Centre SÈVE, Département de Biologie, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada.
authors: Peter
authors: P
authors: Moffett
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
authors: Xiaorong
authors: X
authors: Tao
mesh_terms: D017124:Conserved Sequence; D000090263:Leucine-Rich Repeat Proteins; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D000072417:Protein Domains; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014026:Nicotiana / Q000235:genetics* / Q000821:virology
chemical_list: D000090263:Leucine-Rich Repeat Proteins; D010940:Plant Proteins; D011506:Proteins
keywords: N-terminal domain; Nicotiana benthamiana; Solanum lycopersicum; Tomato spotted wilt tospovirus; coiled-coil (CC); nucleotide-binding leucine-rich repeat (NB-LRR); resistance protein