Host defence peptides from the skin glands of the Australian blue mountains tree-frog Litoria citropa. Solution structure of the antibacterial peptide citropin 1.1.
Nineteen citropin peptides are present in the secretion from the granular dorsal glands of the Blue Mountains tree-frog Litoria citropa; 15 of these peptides are also present in the secretion from the submental gland. Two major peptides, citropin 1.1 (GLFDVIKKVASVIGGL-NH2), citropin 1.2 (GLFDIIKKVASVVGGL-NH2) and a minor peptide, citropin 1.3 (GLFDIIKKVASVIGGL-NH2) are wide-spectrum antibacterial peptides. The amphibian has an endoprotease which deactivates these membrane-active peptides by removing residues from the N-terminal end: loss of three residues gives the most abundant degradation products. The solution structure of the basic peptide citropin 1.1 has been determined by NMR spectroscopy [in a solvent mixture of trifluoroethanol/water (1 : 1)] to be an amphipathic alpha-helix with well-defined hydrophobic and hydrophilic regions. The additional four peptides produced by the dorsal glands are structurally related to the antibacterial citropin 1 peptides but contain three more residues at their C-terminus [e.g. citropin 1.1.3 (GLFDVIKKVASVIGLASP-OH)]. These peptides show minimal antibacterial activity; their role in the amphibian skin is not known.
Wegener
K L
KL
Department of Chemistry, The University of Adelaide, South Australia, Australia.
Wabnitz
P A
PA
Carver
J A
JA
Bowie
J H
JH
Chia
B C
BC
Wallace
J C
JC
Tyler
M J
MJ
D000595:Amino Acid Sequence; D029845:Amphibian Proteins; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides; D001001:Anura; D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology; D011506:Proteins / Q000737:chemistry / Q000494:pharmacology; D017421:Sequence Analysis; D012867:Skin / Q000737:chemistry*
D029845:Amphibian Proteins; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D010455:Peptides; D011506:Proteins; C121829:citropin 1.1 protein, Litoria; C113499:maculatin-1.1 protein, Litoria; C121472:uperin 3.6 peptide, Uperoleia mjobergii