Ca2+‐dependent lipid binding and membrane integration of PopA, a harpin‐like elicitor of the hypersensitive response in tobacco

• DOI: 10.1111/j.1365-2958.2004.04910.x
• Publication Date: 2005-10-18T10:50:02Z
• Authors: Judith Racapé; Lassaad Belbahri; Stefan Engelhardt; Benoit Lacombe; Justin Lee; Jan Lochman; Antoine Marais; Michel Nicole; Thorsten Nürnberger; Francis Parlange; Sandrine Puverel; Harald Keller
• Keywords: Hypersensitive response; Ralstonia solanacearum; Sphingolipid

PopA is released by type III secretion from the bacterial plant pathogen Ralstonia solanacearum and triggers hypersensitive response (HR) in tobacco. The function of remains obscure, mainly because mutants lacking this protein are not altered their ability to interact with plants. In an attempt identify site activity cells, we generated transgenic tobacco plants expressing popA gene under control inducible promoter. Immunocytologic analysis revealed that HR phenotype these correlated presence at plasma membrane. Membrane localization was observed irrespective whether designed accumulate cytoplasm or be secreted cell, suggesting a general lipid-binding ability. We found had high affinity for sterols sphingolipids vitro it required Ca2+ both lipid binding oligomerization. addition, integrated into liposomes membranes Xenopus laevis oocytes where formed ion-conducting pores. These characteristics suggest part system aims attach host cell membrane allow molecules cross barrier.