title: Comparative activity and mechanism of action of three types of bovine antimicrobial peptides against pathogenic Prototheca spp.
abstract: The yeast-like algae of the genus Prototheca are ubiquitous saprophytes causing infections in immunocompromised patients and granulomatous mastitis in cattle. Few available therapies and the rapid spread of resistant strains worldwide support the need for novel drugs against protothecosis. Host defence antimicrobial peptides inactivate a wide array of pathogens and are a rich source of leads, with the advantage of being largely unaffected by microbial resistance mechanisms. Three structurally diverse bovine peptides [BMAP-28, Bac5 and lingual antimicrobial peptide (LAP)] have thus been tested for their capacity to inactivate Prototheca spp. In minimum inhibitory concentration (MIC) assays, they were all effective in the micromolar range against clinical mastitis isolates as well as a Prototheca wickerhamii reference strain. BMAP-28 sterilized Prototheca cultures within 30-60 min at its MIC, induced cell permeabilization with near 100% release of cellular adenosine triphosphate and resulted in extensive surface blebbing and release of intracellular material as observed by scanning electron microscopy. Bac5 and LAP inactivated Prototheca following 3-6 h incubation at fourfold their MIC and did not result in detectable surface damage despite 70-90% killing, suggesting they act via non-lytic mechanisms. In circular dichroism studies, the conformation of BMAP-28, but not that of Bac5 or LAP, was affected by interaction with liposomes mimicking algal membranes. Our results indicate that BMAP-28, Bac5 and LAP kill Prototheca with distinct potencies, killing kinetics, and modes of action and may be appropriate for protothecal mastitis treatment. In addition, the ability of Bac5 and LAP to act via non-lytic mechanisms may be exploited for the development of target-selective drugs.
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, piazzale Kolbe 4, 33100 Udine, Italy.
authors.forename: Linda
authors.initials: L
authors.lastname: Tomasinsig
authors.forename: Barbara
authors.initials: B
authors.lastname: Skerlavaj
authors.forename: Michele
authors.initials: M
authors.lastname: Scarsini
authors.forename: Filomena
authors.initials: F
authors.lastname: Guida
authors.forename: Renata
authors.initials: R
authors.lastname: Piccinini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Tossi
authors.forename: Margherita
authors.initials: M
authors.lastname: Zanetti
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects; D004755:Enterobacteriaceae / Q000187:drug effects; D047091:Eosinophil Granule Proteins / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D008414:Mastitis, Bovine / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010539:Permeability; D017433:Protein Structure, Secondary; D011506:Proteins / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011525:Prototheca / Q000187:drug effects* / Q000302:isolation & purification / Q000648:ultrastructure; D013210:Staphylococcus / Q000187:drug effects; D013291:Streptococcus / Q000187:drug effects; D023083:beta-Defensins / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; C102360:BMAP-28; C078861:CATHL2 protein, Bos taurus; D047091:Eosinophil Granule Proteins; D011506:Proteins; D023083:beta-Defensins; C092480:lingual antimicrobial peptide