Leptoglycin: a new Glycine/Leucine-rich antimicrobial peptide isolated from the skin secretion of the South American frog Leptodactylus pentadactylus (Leptodactylidae).
Antimicrobial peptides are components of innate immunity that is the first-line defense against invading pathogens for a wide range of organisms. Here, we describe the isolation, biological characterization and amino acid sequencing of a novel neutral Glycine/Leucine-rich antimicrobial peptide from skin secretion of Leptodactylus pentadactylus named leptoglycin. The amino acid sequence of the peptide purified by RP-HPLC (C(18) column) was deduced by mass spectrometric de novo sequencing and confirmed by Edman degradation: GLLGGLLGPLLGGGGGGGGGLL. Leptoglycin was able to inhibit the growth of Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli and Citrobacter freundii with minimal inhibitory concentrations (MICs) of 8 microM, 50 microM, and 75 microM respectively, but it did not show antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus, Micrococcus luteus and Enterococcus faecalis), yeasts (Candida albicans and Candida tropicalis) and dermatophytes fungi (Microsporum canis and Trichophyton rubrum). No hemolytic activity was observed at the 2-200 microM range concentration. The amino acid sequence of leptoglycin with high level of glycine (59.1%) and leucine (36.4%) containing an unusual central proline suggests the existence of a new class of Gly/Leu-rich antimicrobial peptides. Taken together, these results suggest that this natural antimicrobial peptide could be a tool to develop new antibiotics.
Sousa
Juliana C
JC
Laboratório de Toxinologia e Farmacologia Molecular, Instituto Superior de Ciências Biomédicas, Universidade Estadual do Ceará, Fortaleza, CE 60.740-000, Brazil.
Berto
Raquel F
RF
Gois
Elicélia A
EA
Fontenele-Cardi
Nauíla C
NC
Honório
José E R
JE
Konno
Katsuhiro
K
Richardson
Michael
M
Rocha
Marcos F G
MF
Camargo
Antônio A C M
AA
Pimenta
Daniel C
DC
Cardi
Bruno A
BA
Carvalho
Krishnamurti M
KM
D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D005260:Female; D005658:Fungi / Q000187:drug effects; D005998:Glycine / Q000737:chemistry; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D007202:Indicators and Reagents; D007930:Leucine / Q000737:chemistry; D008297:Male; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011898:Ranidae / Q000378:metabolism*; D012867:Skin / Q000737:chemistry*
D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D007202:Indicators and Reagents; C543474:leptoglycin, Leptodactylus pentadactylus; D007930:Leucine; D005998:Glycine