Expression and Activity of a Novel Cathelicidin from Domestic Cats

Brian C Leonard,Hiutung Chu,Charles L Bevins,Richard L Gallo,Stanley L Marks,Peter F Moore,Jennifer L Johns,Vladimir N Uversky

doi:10.1371/journal.pone.0018756

Brian C Leonard, Hiutung Chu + Show 6 more

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https://doi.org/10.1371/journal.pone.0018756

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Abstract

Cathelicidins are small cationic antimicrobial peptides found in many species including primates, mammals, marsupials, birds and even more primitive vertebrates, such as the hagfish. Some animals encode multiple cathelicidins in their genome, whereas others have only one. This report identifies and characterizes feline cathelicidin (feCath) as the sole cathelicidin in domestic cats (Felis catus). Expression of feCath is predominantly found in the bone marrow, with lower levels of expression in the gastrointestinal tract and skin. By immunocytochemistry, feCath localizes to the cytoplasm of neutrophils in feline peripheral blood. Structurally, the mature feCath sequence is most similar to a subgroup of cathelicidins that form linear α-helices. feCath possesses antimicrobial activity against E. coli D31, Salmonella enterica serovar Typhimurium (IR715), Listeria monocytogenes and Staphylococcus pseudintermedius (clinical isolate) similar to that of the human ortholog, LL-37. In contrast, feCath lacks the DNA binding activity seen with LL-37. Given its similarity in sequence, structure, tissue expression, and antimicrobial activity, the cathelicidin encoded by cats, feCath, belongs to the subgroup of linear cathelicidins found not only in humans, but also non-human primates, dogs, mice, and rats.

Highlights

Antimicrobial peptides (AMPs) are small, cationic molecules synthesized by epithelial cells and leukocytes throughout the animal kingdom [1]
Identification of feCath cDNA and gene sequence To identify cathelicidins expressed in cats, a 39-RACE strategy was employed using sense PCR primers that anneal to sequences encoding either the signal sequence or the propeptide domains supports that the cat encodes a single feline cathelicidin, we named feCath
Polymorphisms were detected in the signal sequence and propeptide, none were detected in the mature peptide sequence

Summary

Introduction

Antimicrobial peptides (AMPs) are small, cationic molecules synthesized by epithelial cells and leukocytes throughout the animal kingdom [1]. Depending on the specific molecule in question, these peptides are either expressed constitutively or upregulated when exposed to inflammatory stimuli or pathogens These key effector molecules of innate immunity typically possess antimicrobial activity against bacteria, viruses, fungi and/or parasites [1,2]. Cathelin (or cathepsin-L inhibitor) is the unifying feature of the cathelicidins and the amino acid sequence of this prodomain is highly conserved across species [4,5]. Mice, rats and dogs encode a single cathelicidin, whereas other species, such as cows, sheep and pigs, express multiple cathelicidins [6]. In those species with multiple cathelicidins, multiple genes, rather than alternative splicing of primary transcripts, accounts for the diversity. In species where only one cathelicidin is encoded, the mature peptide falls into the a-helical subgroup, in other animals, cathelicidins have diverse structure of the mature peptide

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