Membrane-bound structure and membrane selectivity of cationic antimicrobial peptide Hymenochirin-1Pa and its D9K analog   — ASN Events
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  3. Membrane-bound structure and membrane selectivity of cationic antimicrobial peptide Hymenochirin-1Pa and its D9K analog  

Membrane-bound structure and membrane selectivity of cationic antimicrobial peptide Hymenochirin-1Pa and its D9K analog   (#186)

Akifumi Oyama 1 , Mijiddorj Batsaikhan 2 3 , Kazuyoshi Ueda 2 , Akira Naito 2 , Izuru Kawamura 1 2
  1. Graduate School of Engineering and Science, Yokohama National University, Yokohama, Kanagawa, Japan
  2. Graduate School of Engineering, Yokohama National University, Yokohama, Kanagawa, Japan
  3. School of Engineering and Applied Sciences, National University of Mongolia, Ulaanbaatar, Mongolia

Cationic antimicrobial peptide Hymenochirin-1Pa (H-1Pa) is isolated from the skin secretion of Pseudhymenochirus merlini. H-1Pa shows the strongest activity in Hymenochirin-family against bacteria such as methicillin-resistant S. aureus but has quite low hemolysis [1]. The primary sequence and net charge are as follow: LKLSPKTKDTLKKVLKGAIKGAIAIASMA-NH2 (+7). Previous research showed Asp9 of H-1Pa is possible to have an important role for anti-microbial activity [2]. Here, we investigated the membrane-bound structure of H-1Pa and its analog D9K using by CD, solid-state NMR and MD simulations. Firstly, [2-13C]Leu11, [1-13C]Val14, [2-13C]Gly21 and [3-13C]Ala26-labeled H-1Pa was synthesized by Fmoc-SPPS. We prepared liposome with peptide as a molar ratio of peptide/lipid to 1:20. The lipid components were adjusted to PG:PC:CL = 12:5:1 as S. aureus mimetic membrane and only PC as neutral membrane, respectively. H-1Pa formed mostly alpha-helix in the S. aureus membrane, while it was completely random coil in the PC membrane like that in solution. In addition, the four 13C NMR signals were considerably broadened. It is indicated that H-1Pa tightly binds to the membrane. MD simulations showed the primary contribution of electrostatic interactions to land on the membrane surface and dynamic feature of H-1Pa. Especially, Asp9 forms a strong salt-bridge with Lys13 to make the amphiphilic helical structure having several electrostatic interactions with the membrane. CD pattern of D9K in the S. aureus membrane was dramatically changed, suggesting the decrease of helical content. Our data showed Asp9 is possible to be an important role to stabilize the membrane-bound structure in the S. aureus membrane. We will discuss about the effect of Asp9 on membrane-bound structure and membrane selectivity of H-1Pa.

[1] J. M. Conlon et al. (2013) Comp. Biochem. Physiol. D, 8, 352.

[2] I. Serra et al. (2014) Peptides. 61, 114.