title: Structure-activity relationship of HP (2-20) analog peptide: enhanced antimicrobial activity by N-terminal random coil region deletion.
abstract: HP (2-20) (AKKVFKRLEKLFSKIQNDK) is a 19-aa antimicrobial peptide derived from N-terminus of Helicobacter pylori Ribosomal protein L1 (RpL1). In the previous study, several analogs with amino acid substitutions were designed to increase or decrease only the net hydrophobicity. In particular, substitutions of Gln(16) and Asp(18) with Trp (Anal 3) for hydrophobic amino acid caused a dramatic increase in antibiotic activity without a hemolytic effect. HP-A3 is a potent antimicrobial peptide that forms, in a hydrophobic medium, an amphipathic structure consisting of an N-terminal random coil region (residues 2-5) and extended C-terminal regular alpha-helical region (residues 6-20). To obtain the short and potent alpha-helical antimicrobial peptide, we synthesized a N-terminal random coil deleted HP-A3 (A3-NT) and examined their antimicrobial activity and mechanism of action. The resulting 15mer peptide showed increased antibacterial and antifungal activity to 2- and 4-fold, respectively, without hemolysis. Confocal fluorescence microscopy studies showed that A3-NT was accumulated in the plasma membrane. Flow cytometric analysis revealed that A3-NT acted in salt- and energy-independent manner. Furthermore, A3-NT causes significant morphological alterations of the bacterial surfaces as shown by scanning electron microscopy. Circular dichroism (CD) analysis revealed that A3-NT showed higher alpha-helical contents than the HP-A3 peptide in 50% TFE solution. Therefore, the cell-lytic efficiency of HP-A3, which depended on the alpha-helical content of peptide, correlated linearly with their antimicrobial potency.
authors.affiliation: Research Center for Proteineous Materials, Chosun University, Kwangju, Korea.
authors.forename: Yoonkyung
authors.initials: Y
authors.lastname: Park
authors.forename: Seong-Cheol
authors.initials: SC
authors.lastname: Park
authors.forename: Hae-Kyun
authors.initials: HK
authors.lastname: Park
authors.forename: Song Yub
authors.initials: SY
authors.lastname: Shin
authors.forename: Yangmee
authors.initials: Y
authors.lastname: Kim
authors.forename: Kyung-Soo
authors.initials: KS
authors.lastname: Hahm
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D001426:Bacterial Proteins / Q000737:chemistry* / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects / Q000648:ultrastructure; D005658:Fungi / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000494:pharmacology*; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; C433783:Hp (2-20) protein, Helicobacter pylori; D010446:Peptide Fragments