A Helix-induced Oligomeric Transition of Gaegurin 4, an Antimicrobial Peptide Isolated from a Korean Frog

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Eun, Su-Yong; Jang, Hae-Kyung; Han, Seong-Kyu; Ryu, Pan Dong; Lee, Byeong Jae; Han, Kyou-Hoon; Kim, Soon-Jong
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한국분자·세포생물학회 = Korean Society of Molecular and Cellular Biology
Mol. Cells. 21, 229-236
Aggregation StateAnalytical UltracentrifugeAntimicrobial PeptideGaegurin 4
Gaegurin 4 (GGN4), a novel peptide isolated from the skin of a Korean frog, Rana rugosa, has broad spectrum antimicrobial activity. A number of amphipathic peptides closely related to GGN4 undergo a coil to helix transition with concomitant oligomerization in lipid membranes or membrane-mimicking environments. Despite intensive study of their secondary structures, the oligomeric states of the peptides before and after the transition are not well understood. To clarify the structural basis of its antibiotic action, we used analytical ultracentrifugation to define the aggregation state of GGN4 in water, ethyl alcohol, and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). The maximum size of GGN4 in 15% HFIP corresponded to a decamer, whereas it was monomeric in buffer. The oligomeric transition is accompanied by a cooperative 9 nm blue-shift of maximum fluorescence emission and a large secondary structure change from an almost random coil to an alpha-helical structure. GGN4 induces pores in lipid membranes and, using electrophysiological methods, we estimated the diameter of the pores to be exceed 7.3 A, which suggests that the minimal oligomer structure responsible is a pentamer.
1016-8478 (print)
0219-1032 (online)
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College of Veterinary Medicine (수의과대학)Dept. of Veterinary Medicine (수의학과)Journal Papers (저널논문_수의학과)
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