Arabidopsis thaliana Plant Natriuretic Peptide Active Domain Forms Amyloid-like Fibrils in a pH-Dependent Manner.

Georgia I Nasi,Ioannis P Trougakos,Paraskevi L Tsiolaki,Nikolaos N Louros,Foteini D Aktypi,Vassiliki A Iconomidou,Vassiliki Magafa,Panagiotis M Spatharas

doi:10.3390/plants11010009

Abstract

Plant natriuretic peptides (PNPs) are hormones that have been extracted from many different species, with the Arabidopsis thaliana PNP (AtPNP-A) being the most studied among them. AtPNP-A is a signaling molecule that consists of 130 residues and is secreted into the apoplast, under conditions of biotic or abiotic stress. AtPNP-A has distant sequence homology with human ANP, a protein that forms amyloid fibrils in vivo. In this work, we investigated the amyloidogenic properties of a 34-residue-long peptide, located within the AtPNP-A sequence, in three different pH conditions, using transmission electron microscopy, X-ray fiber diffraction, ATR FT-IR spectroscopy, Congo red and Thioflavin T staining assays. We also utilize bioinformatics tools to study its association with known plant amyloidogenic proteins and other A. thaliana proteins. Our results reveal a new case of a pH-dependent amyloid forming peptide in A. thaliana, with a potential functional role.

Highlights

Amyloid fibrils are formed by proteins or peptides, that under certain conditions self-assemble into characteristic fibrillar structures [1]
The ability of AtPNP-A36–69 to self-assemble and form fibrils with amyloidogenic properties was tested in three different pH conditions, and each solution was incubated for 2–3 weeks at 37 ◦C temperature
The characterization of its aggregates as amyloid-like fibrils was based on the observation of their morphological and structural characteristics according to the basic criteria for the identification of amyloid fibrils [38,39]

Summary

Introduction

Amyloid fibrils are formed by proteins or peptides, that under certain conditions self-assemble into characteristic fibrillar structures [1]. These highly ordered structures are characterized by extreme stability, while conflicting evidence has emerged about the ability of proteases to fragment them [2,3]. The major hallmark of isolated atrial amyloidosis (IAA) is the formation of fibrillar deposits in the atria of the aging heart.

Methods

Results

Conclusion