title: Peptidomic analysis of skin secretions demonstrates that the allopatric populations of Xenopus muelleri (Pipidae) are not conspecific.
abstract: Mueller's clawed frog Xenopus muelleri (Peters 1844) occupies two non-contiguous ranges in east and west Africa. The phylogenetic relationship between the two populations is unclear and it has been proposed that the western population represents a separate species. Peptidomic analysis of norepinephrine-stimulated skin secretions from X. muelleri from the eastern range resulted in the identification of five antimicrobial peptides structurally related to the magainins (magainin-M1 and -M2), xenopsin-precursor fragments (XPF-M1) and caerulein-precursor fragments (CPF-M1 and -M2) previously found in skin secretions of other Xenopus species. A cyclic peptide (WCPPMIPLCSRF.NH₂) containing the RFamide motif was also isolated that shows limited structural similarity to the tigerinins, previously identified only in frogs of the Dicroglossidae family. The components identified in skin secretions from X. muelleri from the western range comprised one magainin (magainin-MW1), one XPF peptide (XPF-MW1), two peptides glycine-leucine amide (PGLa-MW1 and -MW2), and three CPF peptides (CPF-MW1, -MW2 and -MW3). Comparison of the primary structures of these peptides suggest that western population of X. muelleri is more closely related to X. borealis than to X. muelleri consistent with its proposed designation as a separate species. The CPF peptides showed potent, broad-spectrum activity against reference strains of bacteria (MIC 3-25 μM), but were hemolytic against human erythrocytes.
authors.affiliation: Department of Biochemistry, Faculty of Medicine and Health Sciences, United Arab Emirates University, 17666 Al-Ain, United Arab Emirates.
authors.forename: Milena
authors.initials: M
authors.lastname: Mechkarska
authors.forename: Eman
authors.initials: E
authors.lastname: Ahmed
authors.forename: Laurent
authors.initials: L
authors.lastname: Coquet
authors.forename: Jérôme
authors.initials: J
authors.lastname: Leprince
authors.forename: Thierry
authors.initials: T
authors.lastname: Jouenne
authors.forename: Hubert
authors.initials: H
authors.lastname: Vaudry
authors.forename: Jay D
authors.initials: JD
authors.lastname: King
authors.forename: J Michael
authors.initials: JM
authors.lastname: Conlon
mesh_terms: D000351:Africa, Eastern; D000354:Africa, Western; D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D012634:Bodily Secretions / Q000737:chemistry*; D002176:Candida albicans / Q000187:drug effects / Q000254:growth & development; D002851:Chromatography, High Pressure Liquid; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D005260:Female; D049810:Genetic Speciation; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D040901:Proteomics / Q000379:methods*; D012867:Skin / Q000737:chemistry / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D014981:Xenopus / Q000235:genetics / Q000378:metabolism*
chemical_list: D029845:Amphibian Proteins; D023181:Antimicrobial Cationic Peptides