title: Interactions between the plasma membrane and the antimicrobial peptide HP (2-20) and its analogues derived from Helicobacter pylori.
abstract: HP (2-20), a 19-residue peptide derived from the N-terminus of Helicobacter pylori ribosomal protein L1, has antimicrobial activity but is not cytotoxic to human erythrocytes. We synthesized several peptide analogues to investigate the effects of substitutions on structure and antimicrobial activity. Replacement of Gln16 and Asp18 with tryptophan [anal-3 (analogue-3)] caused a dramatic increase in lytic activities against bacteria and fungi. By contrast, a decrease in amphiphilicity caused by replacement of Phe5 or Leu11 with serine was accompanied by a reduction in antimicrobial activity. Analysis of the tertiary structures of the peptides in SDS micelles by NMR spectroscopy revealed that they have a well-defined a-helical structure. Among the analogues, anal-3 has the longest a-helix, from Val4 to Trp18. The enhanced hydrophobicity and increased a-helicity results in enhanced antimicrobial activity in anal-3 without an increase in haemolytic activity. Fluorescence experiments proved that the bacterial-cell selectivity of the anal-3 peptide is due to its high binding affinity for negatively charged phospholipids in bacterial cells. Results showing the effect of spin-labels on the NMR spectra indicated that the side chains in the hydrophobic phase of the amphiphilic a-helix are buried on the surface of the micelle and the tryptophan indole ring is anchored in the membrane surface. Because anal-3 shows high selectivity towards bacterial and fungal cells, it may provide an avenue for the development of new antibiotics.
authors.affiliation: Department of Chemistry and Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea.
authors.forename: Kwang H
authors.initials: KH
authors.lastname: Lee
authors.forename: Dong G
authors.initials: DG
authors.lastname: Lee
authors.forename: Yoonkyung
authors.initials: Y
authors.lastname: Park
authors.forename: Dong-Il
authors.initials: DI
authors.lastname: Kang
authors.forename: Song Y
authors.initials: SY
authors.lastname: Shin
authors.forename: Kyung-Soo
authors.initials: KS
authors.lastname: Hahm
authors.forename: Yangmee
authors.initials: Y
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D048430:Cell Shape / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects; D005658:Fungi / Q000187:drug effects; D016480:Helicobacter pylori / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D014364:Tryptophan
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; C433783:Hp (2-20) protein, Helicobacter pylori; D010446:Peptide Fragments; D014364:Tryptophan