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Abstract
The Arabidopsis nuclear transport receptor IMPORTIN-α3/MOS6 (MODIFIER OF SNC1, 6) is required for constitutive defense responses of the auto-immune mutant snc1 (suppressor of npr1-1, constitutive 1) and contributes to basal disease resistance, suggesting a role in nuclear import of defense-regulatory cargo proteins. We recently showed that MOS6 selectively interacts with TN13, a TIR-NBS protein involved in basal resistance to Pseudomonas syringae pv. tomato (Pst) DC3000 lacking the effectors AvrPto and AvrPtoB. Consistent with a predicted N-terminal transmembrane domain, TN13 localizes to the endoplasmic reticulum (ER) and the nuclear envelope (NE) where it interacts with MOS6 in a transient expression assay. Here, we propose a model that summarizes the subcellular localization, association and function of TN13 and MOS6 in plant defense signaling.
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Affiliation(s)
- Daniel Lüdke
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, Goettingen, Germany
| | - Charlotte Roth
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, Goettingen, Germany
| | - Denise Hartken
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, Goettingen, Germany
| | - Marcel Wiermer
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, Goettingen, Germany
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Roth C, Lüdke D, Klenke M, Quathamer A, Valerius O, Braus GH, Wiermer M. The truncated NLR protein TIR-NBS13 is a MOS6/IMPORTIN-α3 interaction partner required for plant immunity. Plant J 2017; 92:808-821. [PMID: 28901644 DOI: 10.1111/tpj.13717] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 08/21/2017] [Accepted: 09/04/2017] [Indexed: 05/28/2023]
Abstract
Importin-α proteins mediate the translocation of nuclear localization signal (NLS)-containing proteins from the cytoplasm into the nucleus through nuclear pore complexes (NPCs). Genetically, Arabidopsis IMPORTIN-α3/MOS6 (MODIFIER OF SNC1, 6) is required for basal plant immunity and constitutive disease resistance activated in autoimmune mutant snc1 (suppressor of npr1-1, constitutive 1), suggesting that MOS6 plays a role in the nuclear import of proteins involved in plant defense signaling. Here, we sought to identify and characterize defense-regulatory cargo proteins and interaction partners of MOS6. We conducted both in silico database analyses and affinity purification of functional epitope-tagged MOS6 from pathogen-challenged stable transgenic plants coupled with mass spectrometry. We show that among the 13 candidate MOS6 interactors we selected for further functional characterization, the TIR-NBS-type protein TN13 is required for resistance against Pseudomonas syringae pv. tomato (Pst) DC3000 lacking the type-III effector proteins AvrPto and AvrPtoB. When expressed transiently in N. benthamiana leaves, TN13 co-immunoprecipitates with MOS6, but not with its closest homolog IMPORTIN-α6, and localizes to the endoplasmic reticulum (ER), consistent with a predicted N-terminal transmembrane domain in TN13. Our work uncovered the truncated NLR protein TN13 as a component of plant innate immunity that selectively binds to MOS6/IMPORTIN-α3 in planta. We speculate that the release of TN13 from the ER membrane in response to pathogen stimulus, and its subsequent nuclear translocation, is important for plant defense signal transduction.
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Affiliation(s)
- Charlotte Roth
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Daniel Lüdke
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Melanie Klenke
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Annalena Quathamer
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Goettingen, Grisebachstrasse 8, 37077, Goettingen, Germany
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Goettingen, Grisebachstrasse 8, 37077, Goettingen, Germany
| | - Marcel Wiermer
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
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