Arabidopsis LBP/BPI related-1 and -2 bind to LPS directly and regulate PR1 expression.
Lipopolysaccharide (LPS) is a major constituent of the outer membrane of Gram-negative bacteria and acts as a pathogen-associated molecular pattern that triggers immune responses in both plants and animals. LPS-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI), which bind to LPS and play important roles in immunity of mammals, have been well studied. However, the molecule contributing to LPS binding in plants is mostly unknown. The Arabidopsis genome carries two genes encoding LBP/BPI-related proteins which we designated as AtLBP/BPI related-1 (AtLBR-1) and AtLBP/BPI related-2 (AtLBR-2). We found that their N-terminal domains were co-purified with cell wall-derived LPS when expressed in E. coli. Since this finding implied the direct binding of AtLBRs to LPS, we also confirmed binding by using LPS-free AtLBRs and purified LPS. AtLBRs directly bind to both rough and smooth types of LPS. We also demonstrated that LPS-treated atlbr mutant Arabidopsis exhibit a significant delay of induction of defence-related gene pathogenesis-related 1 (PR1) but no other PR genes. Furthermore, LPS-treated atlbr mutants showed defects in reactive oxygen species (ROS) generation. These results demonstrate that, as well as LBP and BPI of mammals, AtLBRs also play an important role in the LPS-induced immune response of plants.
Analytical Research Center for Experimental Sciences, Saga University, 1 Honjo-machi, Saga 840-8502, Japan.|Department of Biological Science and Technology, The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-8580, Japan.
Sayaka
S
Iizasa
Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
Ei'ichi
E
Iizasa
Analytical Research Center for Experimental Sciences, Saga University, 1 Honjo-machi, Saga 840-8502, Japan.|Department of Applied Biochemistry and Food Science, Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan.
Sawako
S
Matsuzaki
Center for Bioscience Research and Education, Utsunomiya University, Tochigi 321-8505, Japan.
Hiroyuki
H
Tanaka
Center for Bioscience Research and Education, Utsunomiya University, Tochigi 321-8505, Japan.
Yutaka
Y
Kodama
Department of Biological Science and Technology, The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-8580, Japan.|Department of Applied Biochemistry and Food Science, Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan.
Keiichi
K
Watanabe
Analytical Research Center for Experimental Sciences, Saga University, 1 Honjo-machi, Saga 840-8502, Japan.|Department of Biological Science and Technology, The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-8580, Japan.
Yukio
Y
Nagano
D000209:Acute-Phase Proteins / Q000235:genetics*; D023181:Antimicrobial Cationic Peptides / Q000235:genetics* / Q000276:immunology; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000276:immunology; D001798:Blood Proteins / Q000235:genetics* / Q000276:immunology; D002352:Carrier Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000276:immunology / Q000472:pathogenicity; D018745:Genome, Plant / Q000276:immunology; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000235:genetics* / Q000276:immunology; D008070:Lipopolysaccharides / Q000235:genetics / Q000276:immunology; D008562:Membrane Glycoproteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology; D000069452:Pathogen-Associated Molecular Pattern Molecules / Q000276:immunology; D057865:Plant Immunity; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D023181:Antimicrobial Cationic Peptides; D029681:Arabidopsis Proteins; D001798:Blood Proteins; D002352:Carrier Proteins; D004693:Glucan Endo-1,3-beta-D-Glucosidase; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D000069452:Pathogen-Associated Molecular Pattern Molecules; D000099231:Lipopolysaccharide-Binding Protein; C021623:bactericidal permeability increasing protein; C077262:PR-1 protein, Arabidopsis; C489849:BGL2 protein, Arabidopsis