title: Insect antimicrobial peptides show potentiating functional interactions against Gram-negative bacteria.
abstract: Antimicrobial peptides (AMPs) and proteins are important components of innate immunity against pathogens in insects. The production of AMPs is costly owing to resource-based trade-offs, and strategies maximizing the efficacy of AMPs at low concentrations are therefore likely to be advantageous. Here, we show the potentiating functional interaction of co-occurring insect AMPs (the bumblebee linear peptides hymenoptaecin and abaecin) resulting in more potent antimicrobial effects at low concentrations. Abaecin displayed no detectable activity against Escherichia coli when tested alone at concentrations of up to 200 μM, whereas hymenoptaecin affected bacterial cell growth and viability but only at concentrations greater than 2 μM. In combination, as little as 1.25 μM abaecin enhanced the bactericidal effects of hymenoptaecin. To understand these potentiating functional interactions, we investigated their mechanisms of action using atomic force microscopy and fluorescence resonance energy transfer-based quenching assays. Abaecin was found to reduce the minimal inhibitory concentration of hymenoptaecin and to interact with the bacterial chaperone DnaK (an evolutionarily conserved central organizer of the bacterial chaperone network) when the membrane was compromised by hymenoptaecin. These naturally occurring potentiating interactions suggest that combinations of AMPs could be used therapeutically against Gram-negative bacterial pathogens that have acquired resistance to common antibiotics.
authors.affiliation: Department of Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology, Winchester Strasse 2, Giessen 35394, Germany.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Rahnamaeian
authors.affiliation: Department of Immunobiology, Institute of Biology and Biochemistry, Maria Curie-Sklodowska University, Akademicka Street 19, Lublin 20-033, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Cytryńska
authors.affiliation: Department of Immunobiology, Institute of Biology and Biochemistry, Maria Curie-Sklodowska University, Akademicka Street 19, Lublin 20-033, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Zdybicka-Barabas
authors.affiliation: Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy and Center of Biotechnology and Biomedicine, University of Leipzig, Deutscher Platz 5, Leipzig 04103, Germany.
authors.forename: Kristin
authors.initials: K
authors.lastname: Dobslaff
authors.affiliation: Department of Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology, Winchester Strasse 2, Giessen 35394, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Wiesner
authors.affiliation: Department of Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology, Winchester Strasse 2, Giessen 35394, Germany TRM Ltd, PO Box 93, York YO43 3WE, UK.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Twyman
authors.affiliation: Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy and Center of Biotechnology and Biomedicine, University of Leipzig, Deutscher Platz 5, Leipzig 04103, Germany.
authors.forename: Thole
authors.initials: T
authors.lastname: Zuchner
authors.affiliation: School of Biological Sciences, Illinois State University, Campus Box 4120, Normal, IL 61790, USA.
authors.forename: Ben M
authors.initials: BM
authors.lastname: Sadd
authors.affiliation: ETH Zürich, Institute of Integrative Biology, ETH-Zentrum CHN, Universitätsstrasse 16, Zürich 8092, Switzerland.
authors.forename: Roland R
authors.initials: RR
authors.lastname: Regoes
authors.affiliation: ETH Zürich, Institute of Integrative Biology, ETH-Zentrum CHN, Universitätsstrasse 16, Zürich 8092, Switzerland.
authors.forename: Paul
authors.initials: P
authors.lastname: Schmid-Hempel
authors.affiliation: Department of Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology, Winchester Strasse 2, Giessen 35394, Germany Institute of Phytopathology and Applied Zoology, Justus-Liebig-University of Giessen, Heinrich-Buff-Ring 26-32, Giessen 35392, Germany andreas.vilcinskas@agrar.uni-giessen.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Vilcinskas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000378:metabolism*; D023181:Antimicrobial Cationic Peptides / Q000235:genetics* / Q000378:metabolism; D001516:Bees / Q000276:immunology* / Q000382:microbiology*; D004926:Escherichia coli / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D013045:Species Specificity
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D019476:Insect Proteins; C080586:hymenoptaecin protein, Apis mellifera; C062933:abaecin protein, Apis mellifera
keywords: abaecin; antimicrobial peptides; bumble bees; hymenoptaecin; innate immunity; insects
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