Download MendeleyA novel beta-defensin structure: big defensin changes its N-terminal structure to associate with the target membrane
Kouno, T., Mizuguchi, M., Aizawa, T., Shinoda, H., Demura, M., Kawabata, S., Kawano, K.(2009) Biochemistry 48: 7629-7635
- PubMed: 19588912
- DOI: https://doi.org/10.1021/bi900756y
- Primary Citation of Related Structures:
2RQ2 - PubMed Abstract:
Big defensin is a 79-residue peptide derived from hemocytes of the Japanese horseshoe crab. The amino acid sequence of big defensin is divided into an N-terminal hydrophobic domain and a C-terminal cationic domain, which are responsible for antimicrobial activities against Gram-positive and -negative bacteria, respectively. The N-terminal domain of big defensin forms a unique globular conformation with two alpha-helices and a parallel beta-sheet, while the C-terminal domain adopts a beta-defensin-like fold. Although our previous study implied that big defensin changes its N-terminal structure in a micellar environment, due to the poor quality of the NMR spectra it remained to be resolved whether the N-terminal domain adopts any structure in the presence of micelles. In this analysis, we successfully determined the structure of the N-terminal fragment of big defensin in a micellar solution, showing that the fragment peptide forms a single alpha-helix structure. Moreover, NMR experiments using paramagnetic probes revealed that the N-terminal domain of big defensin penetrates into the micelle with a dipping at the N-terminal edge of the alpha-helix. Here, we propose a model for how big defensin associates with the target membrane.
Organizational Affiliation:
Faculty of Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan.
