We have investigated structural changes of peptides related to antimicrobial peptide Halictine-1 (HAL-1) induced by interaction with various membrane-mimicking models with the aim to identify a mechanism of the peptide mode of action and to find a correlation between changes of primary/secondary structure and biological activity. Modifications in the HAL-1 amino acid sequence at particular positions, causing an increase of amphipathicity (Arg/Lys exchange), restricted mobility (insertion of Pro) and consequent changes in antimicrobial and hemolytic activity, led to different behavior towards model membranes. Secondary structure changes induced by peptide-membrane interaction were studied by circular dichroism, infrared spectroscopy, and fluorescence spectroscopy. The experimental results were complemented by molecular dynamics calculations. An α-helical structure has been found to be necessary but not completely sufficient for the HAL-1 peptides antimicrobial action. The role of alternative conformations (such as β-sheet, PPII or 310-helix) also seems to be important. A mechanism of the peptide mode of action probably involves formation of peptide assemblies (possibly membrane pores), which disrupt bacterial membrane and, consequently, allow membrane penetration.

• Klíčová slova
• antibacterial peptides, circular dichroism, fluorescence, halictine, infrared spectroscopy,
• MeSH
• antibakteriální látky chemie   metabolismus   MeSH
• fosfatidylcholiny chemie   MeSH
• fosfatidylglyceroly chemie   MeSH
• hydrofobní a hydrofilní interakce MeSH
• kationické antimikrobiální peptidy chemie   metabolismus   MeSH
• kinetika MeSH
• konformace proteinů, alfa-helix MeSH
• konformace proteinů, beta-řetězec MeSH
• lipidové dvojvrstvy chemie   MeSH
• permeabilita MeSH
• sekvence aminokyselin MeSH
• simulace molekulární dynamiky MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• fosfatidylcholiny MeSH
• fosfatidylglyceroly MeSH
• kationické antimikrobiální peptidy MeSH
• lipidové dvojvrstvy MeSH

The assembly of immature retroviral particles is initiated in the cytoplasm by the binding of the structural polyprotein precursor Gag with viral genomic RNA. The protein interactions necessary for assembly are mediated predominantly by the capsid (CA) and nucleocapsid (NC) domains, which have conserved structures. In contrast, the structural arrangement of the CA-NC connecting region differs between retroviral species. In HIV-1 and Rous sarcoma virus, this region forms a rod-like structure that separates the CA and NC domains, whereas in Mason-Pfizer monkey virus, this region is densely packed, thus holding the CA and NC domains in close proximity. Interestingly, the sequence connecting the CA and NC domains in gammaretroviruses, such as murine leukemia virus (MLV), is unique. The sequence is called a charged assembly helix (CAH) due to a high number of positively and negatively charged residues. Although both computational and deletion analyses suggested that the MLV CAH forms a helical conformation, no structural or biochemical data supporting this hypothesis have been published. Using an in vitro assembly assay, alanine scanning mutagenesis, and biophysical techniques (circular dichroism, NMR, microcalorimetry, and electrophoretic mobility shift assay), we have characterized the structure and function of the MLV CAH. We provide experimental evidence that the MLV CAH belongs to a group of charged, E(R/K)-rich, single α-helices. This is the first single α-helix motif identified in viral proteins.

• Klíčová slova
• capsid protein (CA), charged assembly helix (CAH), circular dichroism (CD), electron microscopy (EM), murine leukemia virus (MLV), nuclear magnetic resonance (NMR), retrovirus, single alpha-helix (SAH), spacer peptide (SP), virus assembly,
• MeSH
• mutageneze MeSH
• myši MeSH
• proteinové domény MeSH
• sekundární struktura proteinů MeSH
• virové plášťové proteiny chemie   genetika   MeSH
• virus myší leukemie chemie   genetika   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• virové plášťové proteiny MeSH