Background: Osmotin-Like Proteins (OLPs) have been purified and characterized from
different plant tissues, including latex fluids. Besides its defensive role, tobacco osmotin seems to
induce adiponectin-like physiological effects, acting as an agonist. However, molecular information
about this agonistic effect on adiponectin receptors has been poorly exploited and other osmotins
have not been investigated yet.
Objective and Methods: The present study involved the characterization of three OLPs from
Plumeria rubra latex and molecular docking studies to evaluate the interaction between them and
adiponectin receptors (AdipoR1 and AdipoR2).
Results: P. rubra Osmotin-Like Proteins (PrOLPs) exhibited molecular masses from 21 to 25 kDa
and isoelectric points ranging from 4.4 to 7.7. The proteins have 16 cysteine residues, which are
involved in eight disulfide bonds, conserved in the same positions as other plant OLPs. The threedimensional
(3D) models exhibited the three typical domains of OLPs, and molecular docking
analysis showed that two PrOLP peptides interacted with two adiponectin receptors similarly to
tobacco osmotin peptide.
Conclusion: As observed for tobacco osmotin, the latex osmotins of P. rubra exhibited compatible
interactions with adiponectin receptors. Therefore, these plant defense proteins (without known
counterparts in humans) are potential tools to study modulation of glucose metabolism in type II
diabetes, where adiponectin plays a pivotal role in homeostasis.