Antimicrobial activity of reptile and bird cathelicidins

Abstract

Antimicrobial peptides (AMPs) have been used by animals for millions of years. However, AMPs lack any specific consensus amino-acid sequences that are associated with biological activity, although most of them maintain certain common features, such as containing positive charge and relatively hydrophobic and amphipathic structure. With the increasing number of genomes sequenced and available in the public domain, one alternative methodology to obtain novel AMPs is to analyse genes and proteins from genomic databases to predict and identify amino acid sequences that share similarities and molecular features with natural bioactive peptides. Cathelicidins are found in varying numbers in numerous different species, including reptiles and birds. A remarkable degree of molecular diversity has been noted within this gene family. However, a well-conserved feature across evolutionary distant species is an N-terminal cathelin-domain. Using this domain, we have found two novel cathelicidins from the genome mining of a reptile () and a bird (budgerigar). The in silico structural analysis of the peptides indicated that both of them were alpha helical (Fig. 1), had a positive net charge, with a hydrophobicity around 50% and a Boman index of 0.65 kcal/mol and 3.90 kcal/mol (Table 1).