title: An importin alpha homolog, MOS6, plays an important role in plant innate immunity.
abstract: Plant disease resistance is the consequence of an innate defense mechanism mediated by Resistance (R) genes [1]. The conserved structure of one class of R protein is reminiscent of Toll-like receptors (TLRs) and Nucleotide binding oligomerization domain (NOD) proteins-immune-response perception modules in animal cells [2, 3, and 4]. The Arabidopsis snc1 (suppressor of npr1-1, constitutive, 1) mutant contains a mutation in a TIR-NBS-LRR-type of R gene that renders resistance responses constitutively active without interaction with pathogens [5]. Few components of the downstream signaling network activated by snc1 are known. To search for regulators of R-gene-mediated resistance, we screened for genetic suppressors of snc1. Three alleles of the mutant mos6 (modifier of snc1, 6) partially suppressed constitutive-resistance responses and immunity to virulent pathogens in snc1. Furthermore, the mos6-1 single mutant exhibited enhanced disease susceptibility to a virulent oomycete pathogen. MOS6, identified by positional cloning, encodes importin alpha3, one of eight alpha importins in Arabidopsis [6]. alpha importins mediate the import of specific proteins across the nuclear envelope. We previously reported that MOS3, a protein homologous to human nucleoporin 96, is required for constitutive resistance in snc1 [7]. Our data highlight an essential role for nucleo-cytoplasmic trafficking, especially protein import, in plant innate immunity.
authors.affiliation: Michael Smith Laboratories, Room 301, 2185 East Mall, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Palma
authors.forename: Yuelin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Li
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D028884:Karyopherins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009868:Oomycetes / Q000472:pathogenicity; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010944:Plants / Q000235:genetics* / Q000276:immunology*; D021122:Protein Subunits / Q000235:genetics; D044224:Pseudomonas syringae / Q000472:pathogenicity; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions; D014774:Virulence; D028901:alpha Karyopherins / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; D028884:Karyopherins; C504502:MOS6 protein, Arabidopsis; D021122:Protein Subunits; C482739:SNC1 protein, Arabidopsis; D028901:alpha Karyopherins