title: Physical association of Arabidopsis hypersensitive induced reaction proteins (HIRs) with the immune receptor RPS2.
abstract: Arabidopsis RPS2 is a typical nucleotide-binding leucine-rich repeat resistance protein, which indirectly recognizes the bacterial effector protein AvrRpt2 and thereby activates effector-triggered immunity (ETI). Previously, we identified two hypersensitive induced reaction (AtHIR) proteins, AtHIR1 (At1g09840) and AtHIR2 (At3g01290), as potential RPS2 complex components. AtHIR proteins contain the stomatin/prohibitin/flotillin/HflK/C domain (also known as the prohibitin domain or band 7 domain). In this study, we confirmed that AtHIR1 and AtHIR2 form complexes with RPS2 in Arabidopsis and Nicotiana benthamiana using a pulldown assay and fluorescence resonance energy transfer (FRET) analysis. Arabidopsis has four HIR family genes (AtHIR1-4). All AtHIR proteins could form homo- and hetero-oligomers in vivo and were enriched in membrane microdomains of the plasma membrane. The mRNA levels of all except AtHIR4 were significantly induced by microbe-associated molecular patterns, such as the bacterial flagellin fragment flg22. Athir2-1 and Athir3-1 mutants allowed more growth of Pto DC3000 AvrRpt2, but not Pto DC3000, indicating that these mutations reduce RPS2-mediated ETI but do not affect basal resistance to the virulent strain. Overexpression of AtHIR1 and AtHIR2 reduced growth of Pto DC3000. Taken together, the results show that the AtHIR proteins are physically associated with RPS2, are localized in membrane microdomains, and quantitatively contribute to RPS2-mediated ETI.
authors.affiliation: Department of Plant Biology, Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, Minnesota 55108, USA.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Qi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Tsuda
authors.forename: Le V
authors.initials: le V
authors.lastname: Nguyen
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.forename: Jinshan
authors.initials: J
authors.lastname: Lin
authors.forename: Angus S
authors.initials: AS
authors.lastname: Murphy
authors.forename: Jane
authors.initials: J
authors.lastname: Glazebrook
authors.forename: Hans
authors.initials: H
authors.lastname: Thordal-Christensen
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Katagiri
mesh_terms: D016960:Agrobacterium tumefaciens; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000276:immunology / Q000378:metabolism*; D007113:Immunity, Innate; D021962:Membrane Microdomains; D011485:Protein Binding; D011971:Receptors, Immunologic / Q000378:metabolism*; D014026:Nicotiana
chemical_list: D029681:Arabidopsis Proteins; C089426:RPS2 protein, Arabidopsis; D011971:Receptors, Immunologic