Chemical Synthesis and Functional Analysis of VarvA Cyclotide

• Published in: Molecules (Basel, Switzerland) Vol. 23; no. 4; p. 952
• Main Authors: Álvarez, Claudio A, Santana, Paula A, Luna, Omar, Cárdenas, Constanza, Albericio, Fernando, Romero, María S, Guzmán, Fanny
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 19-04-2018; MDPI
• Subjects: Amino acid sequence; Anti-Infective Agents - chemical synthesis; Anti-Infective Agents - chemistry; Antiinfectives and antibacterials; Antimicrobial activity; Antimicrobial agents; Aquaculture; Bacteria; Chlorine; cyclotide; Cyclotides - chemical synthesis; Cyclotides - chemistry; Disulfide bonds; Fish farms; fish pathogens; Flavobacterium - drug effects; Functional analysis; Gram-negative bacteria; Gram-Negative Bacteria - metabolism; Mass spectrometry; Mass spectroscopy; membrane damage; Microscopy; Molecular chains; Peptide synthesis; Peptides; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tea; Thermal denaturation; antimicrobial activity; membrane damage; cyclotide; fish pathogens
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules23040952

Cyclotides are circular peptides found in various plant families. A cyclized backbone, together with multiple disulfide bonds, confers the peptides’ exceptional stability against protease digestion and thermal denaturation. In addition, the features of these antimicrobial molecules make them suitable for use in animal farming, such as aquaculture. Fmoc solid phase peptide synthesis on 2-chlorotrityl chlorine (CTC) resin using the “tea-bag” approach was conducted to generate the VarvA cyclotide identified previously from
. MALDI-TOF mass spectrometry determined the correct peptide amino acid sequence and the cyclization sites-critical in this multicyclic compound. The cyclotide showed antimicrobial activity against various Gram-negative bacteria, including recurrent pathogens present in Chilean aquaculture. The highest antimicrobial activity was found to be against
. In addition, membrane blebbing on the bacterial surface after exposure to the cyclotide was visualized by SEM microscopy and the Sytox Green permeabilization assay showed the ability to disrupt the bacterial membrane. We postulate that this compound can be proposed for the control of fish farming infections.