title: Characterization of Cimex lectularius (bedbug) defensin peptide and its antimicrobial activity against human skin microflora.
abstract: Antimicrobial peptides are components of both vertebrate and invertebrate innate immune systems that are expressed in response to exposure to bacterial antigens. Naturally occurring antimicrobial peptides from evolutionarily ancient species have been extensively studied and are being developed as potential therapeutics against antibiotic resistant microorganisms. In this study, a putative Cimex lectularius (bedbug, CL) defensin is characterized for its effectiveness against human skin flora including Gram-negative and Gram-positive bacteria. The bedbug defensin (CL-defensin), belonging to family of insect defensins, is predicted to have a characteristic N-terminal loop, an α-helix, and an antiparallel β-sheet, which was supported by circular dichroism spectroscopy. The defensin was shown to be antimicrobial against Gram-positive bacteria commonly found on human skin (Micrococcus luteus, Corynebacterium renale, Staphylococcus aureus and Staphylococcus epidermidis); however, it was ineffective against common skin Gram-negative bacteria (Pseudomonas aeruginosa and Acinetobacter baumannii) under low-salt conditions. CL-defensin was also effective against M. luteus and C. renale in high-salt (MIC) conditions. Our studies indicate that CL-defensin functions by depolarization and pore-formation in the bacterial cytoplasmic membrane.
authors.affiliation: Department of Biology, George Mason University, Manassas, VA, USA.
authors.forename: Akanksha
authors.initials: A
authors.lastname: Kaushal
authors.affiliation: College of Sciences, George Mason University, Fairfax, VA 22030, United States.
authors.forename: Kajal
authors.initials: K
authors.lastname: Gupta
authors.affiliation: School of Systems Biology, George Mason University, Manassas, VA 20110, United States. Electronic address: mvanhoek@gmu.edu.
authors.forename: Monique L
authors.initials: ML
authors.lastname: van Hoek
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018407:Bacterial Physiological Phenomena / Q000187:drug effects*; D001511:Bedbugs / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D023082:Defensins / Q000008:administration & dosage* / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D006801:Humans; D019476:Insect Proteins / Q000008:administration & dosage* / Q000737:chemistry; D064307:Microbiota / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D012867:Skin / Q000187:drug effects* / Q000382:microbiology*
chemical_list: D023082:Defensins; D019476:Insect Proteins
keywords: Antibacterial assay; Antimicrobial peptide; Bed bug; Circular dichroism; Defensin; DiSC(3)5 assay; EC50 assay; Insect antimicrobial peptides; Skin microflora