The characteristic region of arenicin-1 involved with a bacterial membrane targeting mechanism.
The antimicrobial peptide arenicin-1 consists of two antiparallel β-sheets linked by a hydrophilic β-turn. To determine the role of a specific region found in a particular β-sheet structure of the peptide for antibacterial activity, two analogs with N-terminal deletions (RW) and substitutions of Arg to Ala in the β-turn region were designed. In the minimum inhibitory concentration (MIC) test, the antibacterial activities of the analogs were reduced for both Gram-positive and Gram-negative bacteria, when compared to arenicin-1. The influence of the decrease in hydrophobicity on the antibacterial activity was confirmed by a hemolytic assay. Through flow cytometric analysis using propidium iodide (PI) and a 1,6-diphenyl-1,3,5-hexatriene (DPH) assay, it was confirmed that the analogs decreased the degree of plasma membrane permeability compared to arenicin-1. In particular, analog 2 showed a lower permeability in Gram-negative bacteria than in Gram-positive bacteria. The results indicate that a reduction in the net charge weakened the electrostatic interactions between the peptides and the negatively charged membranes. In liposomes, which mimic bacterial membranes, due to a reduced binding affinity to the membranes, the analogs could not deeply penetrate into the hydrocarbon region and induce enough fluorescein isothiocyanate-dextran (FD) leakage compared to that of arenicin-1. It is thought that the Arg residue in the hydrophilic β-turn region is more important to antibacterial activity than the Arg residue in the N-terminal region. This study suggests that the Arg and Trp residues in the N-terminal region and the Arg residue in the β-turn region of arenicin-1 play a key role in antibacterial activity.
School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, 1370 Sankyuk-dong, Puk-ku, Daegu 702-701, Republic of Korea.
Jaeyong
J
Cho
Dong Gun
DG
Lee
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D001419:Bacteria / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects; D005434:Flow Cytometry; D015801:Helminth Proteins; D006461:Hemolysis; D053878:Hemolytic Agents / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D014364:Tryptophan / Q000737:chemistry
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D015801:Helminth Proteins; D053878:Hemolytic Agents; D010455:Peptides; C496888:arenicin-1, Arenicola marina; D014364:Tryptophan