透過您的圖書館登入
IP:44.201.24.171
  • 學位論文

抗菌胜肽/蛋白質對綠膿桿菌抗菌活性之研究

A study in the bactericidal activity of antimicrobial peptide/protein against Pseudomonas aeruginosa

指導教授 : 張大慈 廖有地

摘要


Antimicrobial peptides/proteins (AMPs) are widely distributed in nature with vast diversity. Most AMPs share a common feature of an amphipathic structure where clusters of hydrophobic and cationic amino acids are spatially organized into discrete sectors. Ribonucleases (RNases) are abundant in living organisms and play important roles in RNA metabolism, angiogenesis, neurotoxicity, antitumor and antimicrobial activities, among which antimicrobial RNases possess high positively charged residues. To investigate the role of cationic residues of human RNase7 (hRNase7) in its antimicrobial activities against bacteria and yeast, nuclear magnetic resonance (NMR) spectroscopy and site-directed mutagenesis have been carried out. It is found that 22 positively charged residues (18 Lys and 4 Arg) of hRNase 7 exposed to the surface can be classified into three clusters, and the first cluster containing Lys1, Lys3, Lys111, Lys112 located at a flexible coil near the N terminus, rather than the catalytic residues His15, Lys38, and His123 or other two clusters, Lys32, Lys35 and Lys96, Arg97, Lys100, is critical. For most Gram-negative bacteria, the cell surface lipopolysaccharide (LPS) serves as the major target for AMPs. However, the antimicrobial activities of hRNase 7 and α-helical cationic AMPs against P. aeruginosa, a lethal pathogen to immune-compromised hospitalized patients with low antibiotic susceptibility, can be inhibited by the addition of exogenous OprI (outer membrane protein I) or anti-OprI antibody. The modification and internalization of OprI into cytosol triggered by hRNase 7 make bacterial membrane permeable to intracellular components of P. aeruginosa. Our findings highlight a novel mechanism of antimicrobial activity. This is the first report demonstrating a previously unexplored cell surface target of α-helical cationic AMPs rather than LPS, which may be used for screening drugs to treat antibiotic-resistant bacterial infection.

並列摘要


參考文獻


1. Steiner, H., D. Hultmark, A. Engstrom, H. Bennich, and H. G. Boman. 1981. Sequence and specificity of two antibacterial proteins involved in insect immunity. Nature 292:246-248.
2. Zasloff, M. 1987. Magainins, a class of antimicrobial peptides from Xenopus skin: isolation, characterization of two active forms, and partial cDNA sequence of a precursor. Proceedings of the National Academy of Sciences of the United States of America 84:5449-5453.
3. Bechinger, B., M. Zasloff, and S. J. Opella. 1993. Structure and orientation of the antibiotic peptide magainin in membranes by solid-state nuclear magnetic resonance spectroscopy. Protein Sci 2:2077-2084.
6. Agerberth, B., J. Y. Lee, T. Bergman, M. Carlquist, H. G. Boman, V. Mutt, and H. Jornvall. 1991. Amino acid sequence of PR-39. Isolation from pig intestine of a new member of the family of proline-arginine-rich antibacterial peptides. European journal of biochemistry / FEBS 202:849-854.
8. Montville, T. J., and Y. Chen. 1998. Mechanistic action of pediocin and nisin: recent progress and unresolved questions. Applied microbiology and biotechnology 50:511-519.

被引用紀錄


周羿含(2010)。癌末病患之便秘護理問題處置分析-以某醫學中心為例〔碩士論文,中臺科技大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0099-1901201115491903

延伸閱讀