title: Avirulence protein 3a (AVR3a) from the potato pathogen Phytophthora infestans forms homodimers through its predicted translocation region and does not specifically bind phospholipids.
abstract: The mechanism of translocation of RxLR effectors from plant pathogenic oomycetes into the cytoplasm of their host is currently the object of intense research activity and debate. Here, we report the biochemical and thermodynamic characterization of the Phytophthora infestans effector AVR3a in vitro. We show that the amino acids surrounding the RxLR leader mediate homodimerization of the protein. Dimerization was considerably attenuated by a localized mutation within the RxLR motif that was previously described to prevent translocation of the protein into host. Importantly, we confirm that the reported phospholipid-binding properties of AVR3a are mediated by its C-terminal effector domain, not its RxLR leader. However, we show that the observed phospholipid interaction is attributable to a weak association with denatured protein molecules and is therefore most likely physiologically irrelevant.
authors.affiliation: Aberdeen Oomycete Laboratory, College of Life Sciences and Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, United Kingdom. s.wawra@abdn.ac.uk
authors.forename: Stephan
authors.initials: S
authors.lastname: Wawra
authors.forename: Mark
authors.initials: M
authors.lastname: Agacan
authors.forename: Justin A
authors.initials: JA
authors.lastname: Boddey
authors.forename: Ian
authors.initials: I
authors.lastname: Davidson
authors.forename: Claire M M
authors.initials: CM
authors.lastname: Gachon
authors.forename: Matteo
authors.initials: M
authors.lastname: Zanda
authors.forename: Severine
authors.initials: S
authors.lastname: Grouffaud
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Whisson
authors.forename: Paul R J
authors.initials: PR
authors.lastname: Birch
authors.forename: Andy J
authors.initials: AJ
authors.lastname: Porter
authors.forename: Pieter
authors.initials: P
authors.lastname: van West
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D009154:Mutation; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D055750:Phytophthora infestans / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology; D011485:Protein Binding; D055503:Protein Multimerization; D021382:Protein Sorting Signals / Q000235:genetics; D011198:Solanum tuberosum / Q000382:microbiology; D037521:Virulence Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: C562170:AVR3a protein, Phytophthora infestans; D010743:Phospholipids; D021382:Protein Sorting Signals; D037521:Virulence Factors