Antimicrobial peptide defenses of the Tarahumara frog, Rana tarahumarae

• Published in: Biochemical and biophysical research communications Vol. 297; no. 2; pp. 361 - 367
• Main Authors: Rollins-Smith, Louise A, Reinert, Laura K, Miera, Verma, Conlon, J.Michael
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 20.09.2002
• Subjects: Amino Acid Sequence; Amphibian Proteins; Animals; Antifungal Agents - chemistry; Antifungal Agents - isolation & purification; Antifungal Agents - pharmacology; Antimicrobial Cationic Peptides - chemistry; Antimicrobial Cationic Peptides - isolation & purification; Antimicrobial Cationic Peptides - pharmacology; Antimicrobial peptide; Batrachochytrium dendrobatidis; Brevinin; brevinin-1TRa; Chytrid; Freshwater; Frog skin; Fungi - drug effects; Fungi - pathogenicity; Microbial Sensitivity Tests; Molecular Sequence Data; Peptides; Proteins - chemistry; Proteins - isolation & purification; Proteins - pharmacology; Rana tarahumarae; Ranatuerin; ranatuerin 2; Ranidae - metabolism; Ranidae - microbiology; Skin - chemistry; Mexico; USA, Arizona; Ranatuerin; Chytrid; Frog skin; Brevinin; Rana tarahumarae; Batrachochytrium dendrobatidis; Antimicrobial peptide
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/S0006-291X(02)02217-9

Populations of the Tarahumara frog Rana tarahumarae have decreased markedly in recent years in the northern part of their range. Infection by the chytrid fungus Batrachochytrium dendrobatidis has been implicated in these declines. To determine whether antimicrobial peptides in the skin provide protection against this pathogen, norepinephrine-stimulated skin secretions were tested for their ability to inhibit growth of B. dendrobatidis in vitro. After concentration, crude mixtures of skin peptides inhibited the growth of the chytrid in a concentration-dependent manner. Proteomic analysis led to the identification and characterization of three peptides belonging to the brevinin-1 family of antimicrobial peptides and three belonging to the ranatuerin-2 family. The two most abundant peptides, ranatuerin-2TRa (GIMDSIKGAAKEIAGHLLDNLKCKITGC) and brevinin-1TRa (FLPVIAGIAANVLPKLFCKLTKRC), were active against B. dendrobatidis (MIC of 50 μM for ranatuerin-2TRa and 12.5 μM for brevinin-1TRa against zoospores). These data clearly show that antimicrobial peptides in the skin secretions of the Tarahumara frog are active against B. dendrobatidis and should provide some protection against infection. Therefore, the observed susceptibility of these frogs to this pathogen in the wild may be due to the effects of additional environmental factors that impair this innate defense mechanism, leading to the observed population declines.