The role of plant 90-kDa heat shock proteins in plant immunity

Abstract

Heatshock proteins of 90 kDa (Hsp90) are present in most of the living organisms. Their main function is to preserve cell viability by participating in the assembly, stabilization, maturation and activation of key signaling proteins. Most of the research on Hsp90 functions was made using mammal and yeast models, which has enable considerable progress in the current knowledge about their contribution to maintain cell homeostasis. In this trend, it has been shown that mammal and parasitic Hsp90s may function as immune regulators. Interestingly, recombinant plant Hsp90 is also able to stimulate murine cells and modulate their immune response, suggesting that common regulatory pathways might be evolutionarily conserved. Although plants and mammals present obvious differences in the development of the immune responses against pathogens, several coincidences have been found. Thus, several works demonstrated that plant Hsp90s has an active role in the activation of the defense mechanisms against pathogens, since the lack or deficit of these proteins impair defense against pathogenic bacteria and fungus. This chapter contains an overview of the molecular roles played by plant Hsp90s in the defense against pathogens, and ends with an example of how recombinant plant Hsp90s could be used as adjuvant in vaccine formulations.