title: Identification and structural characterization of novel cyclotide with activity against an insect pest of sugar cane.
abstract: Cyclotides are a family of plant-derived cyclic peptides comprising six conserved cysteine residues connected by three intermolecular disulfide bonds that form a knotted structure known as a cyclic cystine knot (CCK). This structural motif is responsible for the pronounced stability of cyclotides against chemical, thermal, or proteolytic degradation and has sparked growing interest in this family of peptides. Here, we isolated and characterized a novel cyclotide from Palicourea rigida (Rubiaceae), which was named parigidin-br1. The sequence indicated that this peptide is a member of the bracelet subfamily of cyclotides. Parigidin-br1 showed potent insecticidal activity against neonate larvae of Lepidoptera (Diatraea saccharalis), causing 60% mortality at a concentration of 1 μm but had no detectable antibacterial effects. A decrease in the in vitro viability of the insect cell line from Spodoptera frugiperda (SF-9) was observed in the presence of parigidin-br1, consistent with in vivo insecticidal activity. Transmission electron microscopy and fluorescence microscopy of SF-9 cells after incubation with parigidin-br1 or parigidin-br1-fluorescein isothiocyanate, respectively, revealed extensive cell lysis and swelling of cells, consistent with an insecticidal mechanism involving membrane disruption. This hypothesis was supported by in silico analyses, which suggested that parigidin-br1 is able to complex with cell lipids. Overall, the results suggest promise for the development of parigidin-br1 as a novel biopesticide.
authors.affiliation: Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil.
authors.forename: Michelle F S
authors.initials: MFS
authors.lastname: Pinto
authors.affiliation: Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil.
authors.forename: Isabel C M
authors.initials: ICM
authors.lastname: Fensterseifer
authors.affiliation: Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil.
authors.forename: Ludovico
authors.initials: L
authors.lastname: Migliolo
authors.affiliation: Programa de Pós-Graduação em Patologia Molecular, Universidade de Brasília, Brasília-DF, Brazil.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Sousa
authors.affiliation: CENARGEN (Centro Nacional de Pesquisa de Recursos Genéticos e Biotecnologia), Embrapa Recursos Genéticos e Biotecnologia, Brasília-DF, Brazil.
authors.forename: Guy
authors.initials: G
authors.lastname: de Capdville
authors.affiliation: CENARGEN (Centro Nacional de Pesquisa de Recursos Genéticos e Biotecnologia), Embrapa Recursos Genéticos e Biotecnologia, Brasília-DF, Brazil; Departamento de Biologia Celular, Universidade de Brasília, Brasília-DF, Brazil.
authors.forename: Jorge W
authors.initials: JW
authors.lastname: Arboleda-Valencia
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Livestock Industries, 306 Carmody Road, St. Lucia, Queensland 4067, Australia.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Colgrave
authors.affiliation: Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Craik
authors.affiliation: Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil.
authors.forename: Beatriz S
authors.initials: BS
authors.lastname: Magalhães
authors.affiliation: Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil.
authors.forename: Simoni C
authors.initials: SC
authors.lastname: Dias
authors.affiliation: Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil. Electronic address: ocfranco@gmail.com.
authors.forename: Octávio L
authors.initials: OL
authors.lastname: Franco
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D047169:Cyclotides / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D005260:Female; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007306:Insecticides / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D007915:Lepidoptera; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000378:metabolism; D010802:Phylogeny; D011487:Protein Conformation; D019666:Rubiaceae / Q000737:chemistry* / Q000235:genetics; D031786:Saccharum; D012621:Seasons; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
chemical_list: D047169:Cyclotides; D007306:Insecticides; D010767:Phosphorylcholine; C028810:dodecylphosphocholine; D016650:Fluorescein-5-isothiocyanate
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