THE ATPNP-R1 RECEPTOR INTERACTS WITH PLANT (ATPNP-A) AND BACTERIAL (XACPNP) TYPE NATRIURETIC PEPTIDES.

DI PAOLO, V.; MASOTTI, F.; GARAVAGLIA, B.S.; GOTTIG, N.; OTTADO, JORGELINA

Congreso; SAIB 2022; 2022

Natriuretic Peptide (NP) systems have been identified in many vertebrates and are associated with osmoregulatory homeostasis. In higher plants, PNPs are heterologous of animal NPs and elicit a number of responses that are essential in solute and solvent homeostasis and responses to biotrophic pathogens. The Arabidopsis thaliana PNP, AtPNP-A, interacts with a leucine-rich repeat protein denominated AtPNP-R1. Through this interaction, it is able to trigger different responses in plants, to adapt to changes in the environment and regulate internal homeostasis.Xanthomonas citri subsp. citri, the biotrophic bacterial pathogen responsible for citrus canker, also has a PNP-like protein named XacPNP. Our previous results support the hypothesis that XacPNP mimics AtPNP-A in eliciting physiological responses in plants, such as stomatal opening, increases in net water flux and sustains photosynthesis during the early stage of pathogenic infection. We aligned the tertiary structures to AtPNP-A y XacPNP, obtained in silico, and we determined that these are similar even though their amino acid sequences have a percentage of identity of 49%. It is important to mention that amino acids are conserved within the active domain. This, together with previous results, is compatible with the hypothesis of horizontal gene transfer.We were able to determine quantitatively that the receptor AtPNP-R1 is associated with the plasma membrane in plant epidermal cells, and it moves along the membrane and also, intracellularly. For this, we expressed the construct AtPNP-R1-Venus, we labeled the plasma membrane with FM4-64 label and we performed colocalization analyses and plasmolysis assays. Also, we analyzed the interactions between constructs AtPNP-Turquoise – AtPNP-R1-Venus and XacPNP-Turquoise – AtPNP-R1-Venus in planta using colocalization and FRET assays.