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Solution structure of big defensinSolution structure of big defensin
Structural highlights
FunctionBDEF_TACTR Significantly inhibits the growth of Gram-negative and Gram-positive bacteria and fungi in vitro.[1] Publication Abstract from PubMedBig defensin is a 79-residue peptide derived from hemocytes of the Japanese horseshoe crab. It has antimicrobial activities against Gram-positive and -negative bacteria. The amino acid sequence of big defensin can be divided into an N-terminal hydrophobic half and a C-terminal cationic half. Interestingly, the trypsin cleaves big defensin into two fragments, the N-terminal and C-terminal fragments, which are responsible for antimicrobial activity against Gram-positive and -negative bacteria, respectively. To explore the antimicrobial mechanism of big defensin, we determined the solution structure of mature big defensin and performed a titration experiment with DPC micelles. Big defensin has a novel defensin structure; the C-terminal domain adopts a beta-defensin structure, and the N-terminal domain forms a unique globular conformation. It is noteworthy that the hydrophobic N-terminal domain undergoes a conformational change in micelle solution, while the C-terminal domain remains unchanged. Here, we propose that the N-terminal domain achieves its antimicrobial activity in a novel fashion and explain that big defensin has developed a strategy different from those of other beta-defensins to suppress the growth of Gram-positive bacteria. A novel beta-defensin structure: a potential strategy of big defensin for overcoming resistance by Gram-positive bacteria.,Kouno T, Fujitani N, Mizuguchi M, Osaki T, Nishimura S, Kawabata S, Aizawa T, Demura M, Nitta K, Kawano K Biochemistry. 2008 Oct 7;47(40):10611-9. Epub 2008 Sep 12. PMID:18785751[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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