Sequence Divergent RXLR Effectors Share a Structural Fold Conserved across Plant Pathogenic Oomycete Species

Joe Win,Sophien Kamoun,Brian J Staskawicz,Ken Shirasu,Ksenia V Krasileva,Mark J Banfield,Joseph Heitman

doi:10.1371/journal.ppat.1002400

Abstract

The availability of genome sequences for some of the most devastating eukaryotic plant pathogens has led a revolution in our understanding of how these parasites cause disease, and how their hosts respond to invasion [1]–[7]. One of the most significant discoveries from the genome sequences of plant pathogenic oomycetes is the plethora of putative translocated effector proteins these organisms encode. Many effector genes display signatures of rapid evolution and tend to reside in dynamic regions of the pathogen genomes. Once inside the host, effector proteins modulate cellular processes, mainly suppressing plant immunity [8]–[12]. Effectors can also be recognized directly or indirectly by the plant immune system through the action of disease resistance (R) proteins [13], [14].

Highlights

One expanded family of effector proteins is defined by the sequence RXLR (Arg-X-Leu-Arg, where X is any amino acid), which in some cases is followed by an acidic-rich dEER motif (Asp-Glu-Glu-Arg) (Figure 1)
The RXLR motif was originally identified by comparing sequences of effectors from Hyaloperonospora arabidopsidis, Phytophthora infestans, and Phytophthora sojae [15]
It is widely accepted that RXLR effectors are modular proteins comprising an N-terminal secretion signal, followed by the RXLR region, and a C-terminal ‘‘effector’’ domain that encodes the biochemical activity of the protein when expressed directly in plant cells [18,19]

Summary

Introduction

One expanded family of effector proteins is defined by the sequence RXLR (Arg-X-Leu-Arg, where X is any amino acid), which in some cases is followed by an acidic-rich dEER motif (Asp-Glu-Glu-Arg) (Figure 1). Plant Pathogenic Oomycetes Express RXLR Effector Proteins The RXLR motif was originally identified by comparing sequences of effectors from Hyaloperonospora arabidopsidis, Phytophthora infestans, and Phytophthora sojae [15].

Results

Conclusion