Structural elucidation and functional characterization of the Hyaloperonospora arabidopsidis effector protein ATR13

Lauriebeth Leonelli, Jeffery Pelton, Allyn Schoeffler, Douglas Dahlbeck, James Berger, David E. Wemmer, Brian Staskawicz

Research output: Contribution to journalArticlepeer-review

Abstract

The oomycete Hyaloperonospora arabidopsidis (Hpa) is the causal agent of downy mildew on the model plant Arabidopsis thaliana and has been adapted as a model system to investigate pathogen virulence strategies and plant disease resistance mechanisms. Recognition of Hpa infection occurs when plant resistance proteins (R-genes) detect the presence or activity of pathogen-derived protein effectors delivered to the plant host. This study examines the Hpa effector ATR13 Emco5 and its recognition by RPP13-Nd, the cognate R-gene that triggers programmed cell death (HR) in the presence of recognized ATR13 variants. Herein, we use NMR to solve the backbone structure of ATR13 Emco5, revealing both a helical domain and a disordered internal loop. Additionally, we use site-directed and random mutagenesis to identify several amino acid residues involved in the recognition response conferred by RPP13-Nd. Using our structure as a scaffold, we map these residues to one of two surface-exposed patches of residues under diversifying selection. Exploring possible roles of the disordered region within the ATR13 structure, we perform domain swapping experiments and identify a peptide sequence involved in nucleolar localization. We conclude that ATR13 is a highly dynamic protein with no clear structural homologues that contains two surface-exposed patches of polymorphism, only one of which is involved in RPP13-Nd recognition specificity.

Original languageEnglish (US)
Article numbere1002428
JournalPLoS pathogens
Volume7
Issue number12
DOIs
StatePublished - Dec 2011

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Molecular Biology
  • Genetics
  • Virology

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