The Xanthomonas Ax21 protein is processed by the general secretory system and is secreted in association with outer membrane vesicles.
Pattern recognition receptors (PRRs) play an important role in detecting invading pathogens and mounting a robust defense response to restrict infection. In rice, one of the best characterized PRRs is XA21, a leucine rich repeat receptor-like kinase that confers broad-spectrum resistance to multiple strains of the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo). In 2009 we reported that an Xoo protein, called Ax21, is secreted by a type I-secretion system and that it serves to activate XA21-mediated immunity. This report has recently been retracted. Here we present data that corrects our previous model. We first show that Ax21 secretion does not depend on the predicted type I secretion system and that it is processed by the general secretion (Sec) system. We further show that Ax21 is an outer membrane protein, secreted in association with outer membrane vesicles. Finally, we provide data showing that ax21 knockout strains do not overcome XA21-mediated immunity.
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA.
Ofir
O
Bahar
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA.
Rory
R
Pruitt
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA.
Dee Dee
DD
Luu
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA.
Benjamin
B
Schwessinger
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA.
Arsalan
A
Daudi
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA.
Furong
F
Liu
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA.
Randy
R
Ruan
UMR 186 IRD-Cirad-Université Montpellier 2 "Résistance des Plantes aux Bioaggresseurs", Montpellier, France.
Lisa
L
Fontaine-Bodin
UMR 186 IRD-Cirad-Université Montpellier 2 "Résistance des Plantes aux Bioaggresseurs", Montpellier, France.
Ralf
R
Koebnik
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA.|UMR 186 IRD-Cirad-Université Montpellier 2 "Résistance des Plantes aux Bioaggresseurs", Montpellier, France.
Pamela
P
Ronald
Outer membrane vesicles; PAMPs; Plant immunity; Rice; Secretion; XA21; Xanthomonas