title: A nuclear fraction of turnip crinkle virus capsid protein is important for elicitation of the host resistance response.
abstract: The N-terminal 25 amino acids (AAs) of turnip crinkle virus (TCV) capsid protein (CP) are recognized by the resistance protein HRT to trigger a hypersensitive response (HR) and systemic resistance to TCV infection. This same region of TCV CP also contains a motif that interacts with the transcription factor TIP, as well as a nuclear localization signal (NLS). However, it is not yet known whether nuclear localization of TCV CP is needed for the induction of HRT-mediated HR and resistance. Here we present new evidence suggesting a tight correlation between nuclear inclusions formed by CP and the manifestation of HR. We show that a fraction of TCV CP localized to cell nuclei to form discrete inclusion-like structures, and a mutated CP (R6A) known to abolish HR failed to form nuclear inclusions. Notably, TIP-CP interaction augments the inclusion-forming activity of CP by tethering inclusions to the nuclear membrane. This TIP-mediated augmentation is also critical for HR resistance, as another CP mutant (R8A) known to elicit a less restrictive HR, though still self-associated into nuclear inclusions, failed to direct inclusions to the nuclear membrane due to its inability to interact with TIP. Finally, exclusion of CP from cell nuclei abolished induction of HR. Together, these results uncovered a strong correlation between nuclear localization and nuclear inclusion formation by TCV CP and induction of HR, and suggest that CP nuclear inclusions could be the key trigger of the HRT-dependent, yet TIP-reinforced, resistance to TCV.
authors: School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
authors: Sung-Hwan
authors: SH
authors: Kang
authors: School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; Department of Plant Pathology, The Ohio State University, Wooster, OH 44691, USA.
authors: Feng
authors: F
authors: Qu
authors: School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. Electronic address: jmorris1@unl.edu.
authors: T Jack
authors: TJ
authors: Morris
mesh_terms: D029688:Brassica napus / Q000276:immunology* / Q000821:virology; D036022:Capsid Proteins / Q000378:metabolism*; D019184:Carmovirus / Q000276:immunology* / Q000502:physiology*; D002467:Cell Nucleus / Q000737:chemistry / Q000821:virology; D060467:Disease Resistance; D054884:Host-Pathogen Interactions; D045586:Intranuclear Inclusion Bodies / Q000821:virology; D010935:Plant Diseases / Q000276:immunology* / Q000821:virology; D010940:Plant Proteins / Q000378:metabolism; D011485:Protein Binding; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D036022:Capsid Proteins; D010940:Plant Proteins; D014157:Transcription Factors
keywords: Antiviral defense; Carmovirus; GFP; Nuclear localization; Plant virus; Resistance gene; Turnip crinkle virus