title: Nucleocytoplasmic partitioning of tobacco N receptor is modulated by SGT1.
abstract: SGT1 (Suppressor of G2 allele of SKP1) is required to maintain plant disease Resistance (R) proteins with Nucleotide-Binding (NB) and Leucine-Rich Repeat (LRR) domains in an inactive but signaling-competent state. SGT1 is an integral component of a multi-protein network that includes RACK1, Rac1, RAR1, Rboh, HSP90 and HSP70, and in rice the Mitogen-Activated Protein Kinase (MAPK), OsMAPK6. Tobacco (Nicotiana tabacum) N protein, which belongs to the Toll-Interleukin Receptor (TIR)-NB-LRR class of R proteins, confers resistance to Tobacco Mosaic Virus (TMV). Following transient expression in planta, we analyzed the functional relationship between SGT1, SIPK - a tobacco MAPK6 ortholog - and N, using mass spectrometry, confocal microscopy and pathogen assays. Here, we show that tobacco SGT1 undergoes specific phosphorylation in a canonical MAPK target-motif by SIPK. Mutation of this motif to mimic SIPK phosphorylation leads to an increased proportion of cells displaying SGT1 nuclear accumulation and impairs N-mediated resistance to TMV, as does phospho-null substitution at the same residue. Forced nuclear localization of SGT1 causes N to be confined to nuclei. Our data suggest that one mode of regulating nucleocytoplasmic partitioning of R proteins is by maintaining appropriate levels of SGT1 phosphorylation catalyzed by plant MAPK.
authors.affiliation: Institute of Biochemistry and Biophysics PAS, Pawinskiego 5a, 02-106, Warsaw, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Hoser
authors.affiliation: Institute of Biochemistry and Biophysics PAS, Pawinskiego 5a, 02-106, Warsaw, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Żurczak
authors.affiliation: Institute of Biochemistry and Biophysics PAS, Pawinskiego 5a, 02-106, Warsaw, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Lichocka
authors.affiliation: Institute of Biochemistry and Biophysics PAS, Pawinskiego 5a, 02-106, Warsaw, Poland.
authors.forename: Sabina
authors.initials: S
authors.lastname: Zuzga
authors.affiliation: Institute of Biochemistry and Biophysics PAS, Pawinskiego 5a, 02-106, Warsaw, Poland.|Biology Department, Institute of Genetics and Biotechnology, Warsaw University, Pawinskiego 5a, 02-106, Warsaw, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Dadlez
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Dr NW Calgary, Alberta, T2N 1N4, Canada.
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Samuel
authors.affiliation: Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Ellis
authors.affiliation: Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829, Cologne, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Stuttmann
authors.affiliation: Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829, Cologne, Germany.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Parker
authors.affiliation: Institute of Biochemistry and Biophysics PAS, Pawinskiego 5a, 02-106, Warsaw, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Hennig
authors.affiliation: Institute of Biochemistry and Biophysics PAS, Pawinskiego 5a, 02-106, Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Krzymowska
mesh_terms: D002467:Cell Nucleus; D060467:Disease Resistance; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D010935:Plant Diseases / Q000821:virology*; D010940:Plant Proteins / Q000378:metabolism*; D015398:Signal Transduction; D014026:Nicotiana / Q000378:metabolism / Q000502:physiology* / Q000821:virology; D014027:Tobacco Mosaic Virus
chemical_list: D010940:Plant Proteins; D020928:Mitogen-Activated Protein Kinases; C106405:SA-induced protein kinase
keywords: MAPK; NB-LRR; SGT1; disease resistance; nucleocytoplasmic shuttling; protein phosphorylation; tobacco (Nicotiana tabacum)