title: Protegrin structure and activity against Neisseria gonorrhoeae.
abstract: Protegrin 1 (PG-1) is a broad-spectrum antimicrobial peptide that contains 18 amino acid residues (RG GRLCYCRRRFCVCVGR) and has two intramolecular cystine disulfide bonds. To determine the minimal structure responsible for protegrin-mediated activity against Neisseria gonorrhoeae, we synthesized 15 protegrin variants and tested them against two well-characterized gonococcal strains. The MICs of PG-1 were 0.61 microM (1.31 microg/ml) for the serum-sensitive strain F 62 and 0.98 microM (2.11 microg/ml) for the serum-resistant strain FA 19. Six amino acid residues (Arg1, Gly2, Gly3, Arg4, Gly17, and Arg18) and either disulfide bond could be deleted from PG-1 without impairing its potency against strain F 62. In contrast, only Gly17 and Arg18 could be removed without decreasing its activity against FA 19. Protegrin congener 64a (PC-64a; LTYCRRRFCVTV), a variant of PG-1 with 12 amino acid residues and one disulfide bond, displayed MICs of 0.45 microM (0.68 microg/ml) for strain F 62 and 1.37 microM (2.07 microg/ml) for strain FA 19, which approximated those of intact PG-1. Serum-sensitive sac-1+ and sac-3+ transformants of N. gonorrhoeae FA 19 and two FA 19 derivatives with truncated lipooligosaccharide structures were more susceptible to PG-1 and variants with altered disulfide structures. These data suggest that structurally simpler protegrin variants, such as PC-64a, could be used as topical microbicides for N. gonorrhoeae. They also suggest that the cystine-stabilized antiparallel beta-sheet formed by PG-1 residues 5 to 16 is principally responsible for its activity against gonococci.
authors.affiliation: Department of Medicine, UCLA Center for the Health Sciences, Los Angeles, California 90095-1690, USA.
authors.forename: X D
authors.initials: XD
authors.lastname: Qu
authors.forename: S S
authors.initials: SS
authors.lastname: Harwig
authors.forename: W M
authors.initials: WM
authors.lastname: Shafer
authors.forename: R I
authors.initials: RI
authors.lastname: Lehrer
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D002240:Carbohydrate Sequence; D004220:Disulfides / Q000737:chemistry; D004352:Drug Resistance, Microbial; D008070:Lipopolysaccharides / Q000737:chemistry; D008969:Molecular Sequence Data; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000235:genetics; D011506:Proteins / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014169:Transformation, Bacterial
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D004220:Disulfides; D008070:Lipopolysaccharides; D011506:Proteins; C023023:lipid-linked oligosaccharides; C094880:protegrin-1