Characterization of a Novel Peptide from Pathogenic <i>Leptospira</i> and Its Cytotoxic Effect

• Main Authors: Saksakon Paratsaphan, Saengduen Moonsom, Onrapak Reamtong, Sittiruk Roytrakul, Vanaporn Wuthiekanun, Nicholas P. J. Day, Piengchan Sonthayanon
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Pathogens
• Subjects: novel peptide; pathogenic <i>Leptospira</i>; cytotoxicity
• Online Access: https://www.mdpi.com/2076-0817/9/11/906

Leptospirosis is a zoonotic infectious disease caused by pathogenic <i>Leptospira</i> species. Virulence proteins have been shown to be key determinants of the pathogenesis of pathogenic <i>Leptospira</i>. A specific peptide at a mass-to-charge ratio of 7000 Da was identified in <i>Leptospira</i> whole cells using matrix-assisted laser/desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. This peptide was specifically present in pathogenic <i>Leptospira</i> 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 <i>L. interrogans</i> 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.