Role of C-terminal heptapeptide in pore-forming activity of antimicrobial agent, gaegurin 4

H. J. Kim, S. S. Kim, M. H. Lee, B. J. Lee, P. D. Ryu

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Gaegurin 4 (GGN4) is an antimicrobial peptide of 37 amino acids isolated from the skin of a frog, Rana rugosa. GGN4 has a disulfide bond between the residues 31 and 37, which is highly conserved among the antimicrobial peptides isolated from skin of the genus, Rana. However, the role of this C-terminal heptapeptide motif is not well understood. In this work, we compared the membrane effects of the full-length GGN4 (C37) and GGN4 1-30 (C30), which is devoid of the C-terminal seven amino acids to elucidate the function of the C-terminal motif. C37 induced significantly larger membrane conductance (>10x) in the model lipid bilayers formed with acidic and neutral phospholipids and larger K+ efflux from gram-positive (>30x) and gram-negative bacteria. However, the pores induced by C37 and C30 were not different in their permeability to K+ over Cl- (permeability ratio of K+ to Cl- = 4.8-7.1). In addition, the pore-forming effect of C37 or C30 in acidic membranes was not different from that in neutral membranes. Furthermore, C37-induced K+ efflux was not significantly decreased by the reducing agent, dithiothreitol. The results indicate that C-terminal heptapeptide sequence plays an important role in maintaining the high pore-forming activity of GGN4, but does not participate in forming GGN4-induced pore structure. The disulfide bond in this region does not appear critical for such high ionophoric activity of GGN4.

Original languageEnglish (US)
Pages (from-to)151-158
Number of pages8
JournalJournal of Peptide Research
Issue number4
StatePublished - Oct 2004
Externally publishedYes


  • Antimicrobial peptide
  • Disulfide bond
  • Gaegurin 4
  • Membrane conductance
  • Potassium efflux

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology


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