title: Structure-activity relations of parasin I, a histone H2A-derived antimicrobial peptide.
abstract: The structure-activity relations and mechanism of action of parasin I, a 19-amino acid histone H2A-derived antimicrobial peptide, were investigated. Parasin I formed an amphipathic alpha-helical structure (residues 9-17) flanked by two random coil regions (residues 1-8 and 18-19) in helix-promoting environments. Deletion of the lysine residue at the N-terminal [Pa(2-19)] resulted in loss of antimicrobial activity, but did not affect the alpha-helical content of the peptide. The antimicrobial activity was recovered when the lysine residue was substituted with another basic residue, arginine ([R(1)]Pa), but not with polar, neutral, or acidic residues. Progressive deletions from the C-terminal [Pa(1-17), Pa(1-15)] slightly increased the antimicrobial activity (1-4 microg/ml) without affecting the alpha-helical content of the peptide. However, further deletion [Pa(1-14)] resulted in nearly complete loss of antimicrobial activity and alpha-helical structure. Confocal microscopic analysis and membrane permeabilization assays showed that parasin I and its analogs with comparable antimicrobial activities localized to the cell membrane and subsequently permeabilized the outer and cytoplasmic membranes. Pa(1-14) also localized to the cell membrane, but lost membrane-permeabilizing activity, whereas Pa(2-19) showed poor membrane-binding and -permeabilizing activities. The results indicate that the basic residue at the N-terminal is essential for the membrane-binding activity of parasin I, and among the membrane-binding parasin I analogs, the alpha-helical structure is necessary for the membrane-permeabilizing activity.
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Young Sook
authors.initials: YS
authors.lastname: Koo
authors.forename: Jung Min
authors.initials: JM
authors.lastname: Kim
authors.forename: In Yup
authors.initials: IY
authors.lastname: Park
authors.forename: Byung Jo
authors.initials: BJ
authors.lastname: Yu
authors.forename: Su A
authors.initials: SA
authors.lastname: Jang
authors.forename: Key-Sun
authors.initials: KS
authors.lastname: Kim
authors.forename: Chan Bae
authors.initials: CB
authors.lastname: Park
authors.forename: Ju Hyun
authors.initials: JH
authors.lastname: Cho
authors.forename: Sun Chang
authors.initials: SC
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology; D002463:Cell Membrane Permeability; D002942:Circular Dichroism; D005658:Fungi / Q000187:drug effects; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006657:Histones / Q000737:chemistry* / Q000494:pharmacology / Q000502:physiology; D057927:Hydrophobic and Hydrophilic Interactions; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology / Q000502:physiology; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D006657:Histones; D010446:Peptide Fragments; D011506:Proteins; C115701:parasin I