Antimicrobial characterization of human beta-defensin 3 derivatives.
Human beta-defensin 3 (hBD3) is a highly basic 45-amino-acid protein that acts both as an antimicrobial agent and as a chemoattractant molecule. Although the nature of its antimicrobial activity is largely electrostatic, the importance of the molecular structure on this activity is poorly understood. Two isoforms of hBD3 were synthesized: the first with native disulfide linkages and the second with nonnative linkages. In a third synthetic peptide, all cysteine residues were replaced with alpha-aminobutyric acid, creating a completely linear peptide. A series of six small, linear peptides corresponding to regions of hBD3 with net charges ranging from +4 to +8 (at pH 7) and lengths ranging from 9 to 20 amino acids were also synthesized. The linear full-length peptide showed the highest microbicidal activity against Escherichia coli and Staphylococcus aureus, while all three full-length forms showed equal activity against Candida albicans. The linear peptide also showed high activity against Enterococcus faecium and Pseudomonas aeruginosa. Peptides corresponding to the C terminus showed higher activities when tested against E. coli, with the most active peptides being the most basic. However, only the peptide corresponding to the N terminus of hBD3 showed any activity against S. aureus and C. albicans. Further, N-terminal deletion mutants of native hBD3 showed diminished activities against S. aureus. Thus, the antimicrobial properties of hBD3 derivatives are determined by both charge and structure.
Hoover
David M
DM
Macromolecular Crystallography Laboratory, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA.
Wu
Zhibin
Z
Tucker
Kenneth
K
Lu
Wuyuan
W
Lubkowski
Jacek
J
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D015169:Colony Count, Microbial; D005658:Fungi / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship; D023083:beta-Defensins / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; C422950:DEFB103A protein, human; D023083:beta-Defensins