期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 97, 期 21, 页码 11221-11226出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.210301097
关键词
cationic antibacterial peptides; NMR solution structure; five-helix globule; cyclic polypeptide; membrane permeation
The solution structure of bacteriocin AS-48, a 70-residue cyclic polypeptide from Enterococcus faecalis. consists of a globular arrangement of five alpha-helices enclosing a compact hydrophobic core. The head-to-tail union lies in the middle of helix 5. a fact that is shown to have a pronounced effect on the stability of the three-dimensional structure. Positive charges in the side chains of residues in helix 4 and in the turn linking helix 4 to helix 5 form a cluster that most probably determine its antibacterial activity by promoting pore formation in cell membranes. A similar five-helix structural motif has been found in the antimicrobial NK-lysin. an effector polypeptide of T and natural killer (NK) cells. Bacteriocin AS-48 lacks the three disulfide bridges characteristic of the saposin fold present in NK-lysin, and has no sequence homology with it. Nevertheless, the similar molecular architecture and high positive charge strongly suggest a common mechanism of antibacterial action.
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