Characterization of a Novel Peptide from Pathogenic Leptospira and Its Cytotoxic Effect.

Saksakon Paratsaphan,Sittiruk Roytrakul,Nicholas P J Day,Piengchan Sonthayanon,Onrapak Reamtong,Vanaporn Wuthiekanun,Saengduen Moonsom

doi:10.3390/pathogens9110906

Abstract

Leptospirosis is a zoonotic infectious disease caused by pathogenic Leptospira species. Virulence proteins have been shown to be key determinants of the pathogenesis of pathogenic Leptospira. A specific peptide at a mass-to-charge ratio of 7000 Da was identified in Leptospira whole cells using matrix-assisted laser/desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. This peptide was specifically present in pathogenic Leptospira and in clinical isolates. We report here the characterization of this specific peptide using a proteomics approach. This peptide was significantly matched to a hypothetical conserved L. interrogans protein (LA2458) with a calculated molecular weight of 7140.136 Da containing a tellurite-resistance domain at its C terminus (TerB-C). The amino acid sequences revealed the presence of hydrophobic transmembrane portions and two linear B-cell epitopes. Despite its low abundance, this synthetic peptide demonstrated dose-dependent cytotoxicity toward African green monkey kidney (Vero) cells via the apoptosis pathway. The concentration of the peptide 100 µM induced about 50% of cell death after a 24 h exposure. This peptide could be useful for the diagnosis of leptospirosis and the study of pathogenesis.

Highlights

Pathogenic Leptospira species are the causative agent of leptospirosis, which is a widespread zoonosis with one million estimated cases that results in 60,000 deaths annually [1]
The specific peptide generated by MALDI-TOF MS, which was found exclusively in pathogenic
The peptide in our study was presented in a cell pellet, which might suggest that the peptide could be a cell membrane-associated peptide

Summary

Introduction

Pathogenic Leptospira species are the causative agent of leptospirosis, which is a widespread zoonosis with one million estimated cases that results in 60,000 deaths annually [1]. Humans are the accidental hosts of pathogenic Leptospira spp. The invaded leptospires circulate via the bloodstream to multiple organs and may cause kidney damage and renal failure [3]. The symptoms of human leptospirosis may vary from mild flu-like symptoms to severe multi-organ failure. The mechanisms underlying the multi-organ failure caused by pathogenic Leptospira remain unclear. Virulent proteins associated with host cell damage and pathogenesis are the major focus of therapeutic and vaccine research [4]. The discovery of a factor associated with host-cell toxicity may provide insights into the mechanisms of pathogenesis of Pathogens 2020, 9, 906; doi:10.3390/pathogens9110906 www.mdpi.com/journal/pathogens

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