Discovery of antimicrobial peptides in spider silk glands using Expressed Sequence Tag data

Abstract

Antimicrobial peptides (AMP) emerge as a novel solution to the increasing problem of antibiotic resistance. AMPs have been described in several organisms by experimental or in silico analysis, but little efforts have been made to screen AMP in promising biomaterials such as spider silk. Spider silk is at high risk of microorganism infections from being exposed directly to the environment, and several reports show that this biomaterial can inhibit their growth. Although the mechanisms behind antimicrobial defense of spider silk is still unknow, studies suggest the presence of antimicrobial compounds. Here, I designed and implemented a pipeline to mine AMP from Expressed Sequence Tag (EST) data of spider silk gland tissues based on alignments with AMP databases and Hidden Markov Models profiles of AMP families. Using six EST datasets, we discovered five known and three novel peptides that are expressed in spider silk glands. Known peptides are suggested to be part of the humoral immune system of spiders. One of the three novel peptides has the potential to be antimicrobial due to its amphipathic structure, demonstrating the potential of spider silk glands as a source of AMPs. Although most peptides were discovered from silk glands, they need to be screened in silk once it is in the environment.