Abstract
With their wide repertoire of mechanisms, antimicrobial peptides (AMPs) are promising alternatives to fight against varied pathogenic microorganisms (bacteria, fungi, viruses, parasites, etc.). AMPs, novel components of the innate immune defense system, are secreted by all organisms. The aquatic environment represents a huge population and an enormous source of varied AMPs. Polyphemusin-I, a marine AMP isolated from hemocytes of an American horseshoe crab, possesses high antimicrobial activities. Studies on polyphemusin-I have verified the intracellular mechanisms of action, however, its intracellular targets are not yet explored. In this study, we employed Escherichia coli proteome microarrays to systematically screen the entire intracellular protein targets of polyphemusin-I. A total of 97 protein targets of polyphemusin-I were statistically analyzed from the quadruplicate Escherichia coli proteome microarrays assays. Among these identified protein targets, 56 proteins had cellular location inside the cell (i.e., cytoplasm), one in the plasma membrane, one in the periplasm and the rest 39 proteins had no specified cellular location. The bioinformatics analysis of these identified protein targets of polyphemusin-I in gene ontology (GO) enrichment category of molecular function revealed significant enrichment in nucleic acid related GO terms i.e., “RNA binding”, “nucleotide binding”, “nuclease activities”, “uracil DNA N-glycosylase activities” and others. Moreover, enrichment in GO category of biological process also depicted enrichment in nucleic acid related GO terms, such as “nucleic acid phosphodiester bond hydrolysis”, “deoxyribonucleotide metabolism”, and others. In accordance to GO enrichment analysis, protein families (PFAM) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis also showed significant enrichment in nucleic acid terms. These enrichment results suggest that polyphemusin-I targets nucleic acid-associated proteins. Furthermore, to provide a comprehensive study, we compared the identified protein targets of polyphemusin-I with previously identified protein targets of four AMPs (P-Der, Lfcin B, PR-39, and Bac 7) using Escherichia coli proteome microarrays. The comparison study of five AMPs (polyhemusin-I, P-Der, Lfcin B, PR-39, and Bac 7) showed only nine common protein targets in all the five AMPs, whereas a total of 39 and 43 common protein targets were identified among the two marine AMPs (polyphemusin-I and P-Der) and three terrestrial AMPs (Lfcin B, PR-39 and Bac7), respectively. To further reveal the target pattern of marine and terrestrial AMPs, the enrichment results obtained from common protein targets of marine AMPs with terrestrial AMPs were compared. The comparison result indicated that AMPs have unique mechanism of action among marine or terrestrial AMPs. Hence, in this study, we have not only identified the intracellular protein targets of polyphemusin-I, but also revealed the protein target differences between marine AMPs and terrestrial AMPs.
Highlights
As a priority to search for novel antibiotics against the increasing number of multidrug resistance pathogens, the naturally produced antimicrobial peptides (AMPs) found in the body fluids and tissues of all organisms are extensively studied [1,2]
Biotinylated polyphemusin-I was probed on the high-throughput Escherichia coli proteome microarrays for systematical screening of the entire potential protein targets of polyphemusin-I
We have explored the entire intracellular protein targets of polyphemsuinI using Escherichia coli proteome microarrays
Summary
As a priority to search for novel antibiotics against the increasing number of multidrug resistance pathogens, the naturally produced antimicrobial peptides (AMPs) found in the body fluids and tissues of all organisms (i.e., prokaryotic to eukaryotic) are extensively studied [1,2]. AMPs inhibit the action of pathogenic cytokines, like lipoteichoic acid and lipopolysaccharide (LPS) [4]. AMPs are unique, short sequence peptides (
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
