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Identification, structural characterisation and expression analysis of a defensin gene from the tiger beetle Calomera littoralis (Coleoptera: Cicindelidae)

Rodríguez-García, María Juliana, García-Reina, Andrés, Machado, Vilmar, Galián, José
Gene 2016 v.589 no.1 pp. 56-62
Cicindelinae, Escherichia coli, bioinformatics, cysteine, disulfide bonds, gene expression regulation, genes, isoelectric point, lipopolysaccharides, open reading frames, phylogeny, quantitative polymerase chain reaction
In this study, a defensin gene (Clit-Def) has been characterised in the tiger beetle Calomera littoralis for the first time. Bioinformatic analysis showed that the gene has an open reading frame of 246bp that contains a 46 amino acid mature peptide. The phylogenetic analysis showed a high variability in the coleopteran defensins analysed. The Clit-Def mature peptide has the features to be involved in the antimicrobial function: a predicted cationic isoelectric point of 8.94, six cysteine residues that form three disulfide bonds, and the typical cysteine-stabilized α-helix β-sheet (CSαβ) structural fold. Real time quantitative PCR analysis showed that Clit-Def was upregulated in the different body parts analysed after infection with lipopolysaccharides of Escherichia coli, and also indicated that has an expression peak at 12h post infection. The expression patterns of Clit-Def suggest that this gene plays important roles in the humoral system in the adephagan beetle Calomera littoralis.