title: Selective reciprocity in antimicrobial activity versus cytotoxicity of hBD-2 and crotamine.
abstract: Recent discoveries suggest cysteine-stabilized toxins and antimicrobial peptides have structure-activity parallels derived by common ancestry. Here, human antimicrobial peptide hBD-2 and rattlesnake venom-toxin crotamine were compared in phylogeny, 3D structure, target cell specificity, and mechanisms of action. Results indicate a striking degree of structural and phylogenetic congruence. Importantly, these polypeptides also exhibited functional reciprocity: (i) they exerted highly similar antimicrobial pH optima and spectra; (ii) both altered membrane potential consistent with ion channel-perturbing activities; and (iii) both peptides induced phosphatidylserine accessibility in eukaryotic cells. However, the Na(v) channel-inhibitor tetrodotoxin antagonized hBD-2 mechanisms, but not those of crotamine. As crotamine targets eukaryotic ion channels, computational docking was used to compare hBD-2 versus crotamine interactions with prototypic bacterial, fungal, or mammalian Kv channels. Models support direct interactions of each peptide with Kv channels. However, while crotamine localized to occlude Kv channels in eukaryotic but not prokaryotic cells, hBD-2 interacted with prokaryotic and eukaryotic Kv channels but did not occlude either. Together, these results support the hypothesis that antimicrobial and cytotoxic polypeptides have ancestral structure-function homology, but evolved to preferentially target respective microbial versus mammalian ion channels via residue-specific interactions. These insights may accelerate development of anti-infective or therapeutic peptides that selectively target microbial or abnormal host cells.
authors.affiliation: Division of Infectious Diseases, LAC-Harbor University of California, Los Angeles Medical Center, Torrance, CA 90509, USA.
authors.forename: Nannette Y
authors.initials: NY
authors.lastname: Yount
authors.forename: Deborah
authors.initials: D
authors.lastname: Kupferwasser
authors.forename: Alberto
authors.initials: A
authors.lastname: Spisni
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Dutz
authors.forename: Zachary H
authors.initials: ZH
authors.lastname: Ramjan
authors.forename: Shantanu
authors.initials: S
authors.lastname: Sharma
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Waring
authors.forename: Michael R
authors.initials: MR
authors.lastname: Yeaman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000633:toxicity; D055592:Biophysical Phenomena; D002478:Cells, Cultured; D003435:Crotalid Venoms / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology / Q000633:toxicity; D017839:Crotalus; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D050296:Microbial Viability / Q000187:drug effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013211:Staphylococcus aureus / Q000187:drug effects; D023083:beta-Defensins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology / Q000633:toxicity
chemical_list: D000900:Anti-Bacterial Agents; D003435:Crotalid Venoms; C106641:DEFB4A protein, human; D023083:beta-Defensins; C010563:crotamine
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