Primate cathelicidin orthologues display different structures and membrane interactions

2009 ◽  
Vol 417 (3) ◽  
pp. 727-735 ◽  
Author(s):  
Francesca Morgera ◽  
Lisa Vaccari ◽  
Nikolinka Antcheva ◽  
Denis Scaini ◽  
Sabrina Pacor ◽  
...  
Keyword(s):  
Host Cell ◽  
Structural Characteristics ◽  
Attenuated Total Reflection ◽  
Model Membranes ◽  
Helical Conformation ◽  
Bulk Solution ◽  
Free Form ◽  
Outer Cell ◽  
Membrane Interactions ◽  
Aggregation State

The human cathelicidin LL-37 displays both direct antibacterial activities and the capacity to modulate host-cell activities. These depend on structural characteristics that are subject to positive selection for variation, as observed in a previous analysis of the CAMP gene (encoding LL-37) in primates. The altered balance between cationic and anionic residues in different primate orthologues affects intramolecular salt-bridging and influences the stability of the helical conformation and tendency to aggregate in solution of the peptide. In the present study, we have analysed the effects of these structural variations on membrane interactions for human LL-37, rhesus RL-37 and orang-utan LL-37, using several complementary biophysical and biochemical methods. CD and ATR (attenuated total reflection)-FTIR (Fourier-transform IR) spectroscopy on model membranes indicate that RL-37, which is monomeric and unstructured in bulk solution [F-form (free form)], and human LL-37, which is partly structured and probably aggregated [A-form (aggregated form)], bind biological membranes in different manners. RL-37 may insert more deeply into the lipid bilayer than LL-37, which remains aggregated. AFM (atomic force microscopy) performed on the same supported bilayer as used for ATR-FTIR measurements suggests a carpet-like mode of permeabilization for RL37 and formation of more defined worm-holes for LL-37. Comparison of data from the biological activity on bacterial cells with permeabilization of model membranes indicates that the structure/aggregation state also affects the trajectory of the peptides from bulk solution through the outer cell-wall layers to the membrane. The results of the present study suggest that F-form cathelicidin orthologues may have evolved to have primarily a direct antimicrobial defensive capacity, whereas the A-forms have somewhat sacrificed this to gain host-cell modulating functions.

scholarly journals Preparation and Characterization of Immobilized Molybdenum Complex on Pillared Montmorillonite K-10

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Farah Wahida Harun ◽  
Siti Balkis Mahamat Nor ◽  
Siti Salhah Othman
Keyword(s):  
Structural Characteristics ◽  
Xrd Analysis ◽  
Attenuated Total Reflection ◽  
Basal Spacing ◽  
Molybdenum Complex ◽  
X Ray ◽  
Pillared Montmorillonite ◽  
Sem Micrograph ◽  
Pillaring Solution

This study was carried out to immobilize molybdenyl (VI) acetylacetonate (MoO2(acac)2) complex on alumina pillared montmorillonite K-10 (MMT K-10). Pillar MMT K-10 was produced by introducing MMT K-10 with a hydrolysis solution of NaOH with AlCl3. Different concentrations of pillaring solution were prepared in terms of OHto Al3+ ratio (0.5, 1.0, 1.5 and 2.0) to observe the structural characteristics of MMT K-10. The pillared materials were then immobilized with 0.1 M MoO2(acac)2 and were characterized using X-ray diffractometry (XRD), scanning electron microscopy coupled in an energy dispersive X-ray spectrometer (SEM-EDX) and Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) techniques. FTIR bands at ca. 890 – 930 cm-1 indicate that the Mo complex was immobilized on the surface of pillared MMT K-10 not in between the layers. This is supported by the SEM and XRD analysis where the SEM micrograph showed deposition of Mo on the surface of MMT K-10 as well as no modification of basal spacing was observed by XRD. Meanwhile, the d(001) spacing of the alumina pillared MMT K10 samples were seen to increase slightly as the concentration of OH/Al3+ increased.

Influence of lipid composition of model membranes on methacrylate antimicrobial polymer–membrane interactions

Soft Matter ◽  
2017 ◽  
Vol 13 (41) ◽  
pp. 7665-7676 ◽  
Author(s):  
Upayan Baul ◽  
Satyavani Vemparala
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Lipid Composition ◽  
Polymer Membrane ◽  
Model Membranes ◽  
Membrane Interactions ◽  
Dynamics Simulations

Using atomistic molecular dynamics simulations, the role of lipid composition in the interactions of multiple methacrylate antimicrobial polymer agents with model membranes, and the consequent response of the membranes is studied.

scholarly journals Membrane interactions and uncoating of Aichi virus, a picornavirus that lacks a VP4

2022 ◽  
Author(s):  
James Kelly ◽  
Jessica Swanson ◽  
Joseph Newman ◽  
Elisabetta Groppelli ◽  
Nicola Stonehouse ◽  
...  
Keyword(s):  
Pore Formation ◽  
Sequence Similarity ◽  
Critical Role ◽  
Foot And Mouth Disease ◽  
Model Membranes ◽  
Aichi Virus ◽  
Membrane Interactions ◽  
Membrane Pore ◽  
Animal Pathogens ◽  
Mouth Disease Virus

Kobuviruses are an unusual and poorly characterised genus within the picornavirus family, and can cause gastrointestinal enteric disease in humans, livestock and pets. The human Kobuvirus, Aichi virus (AiV) can cause severe gastroenteritis and deaths in children below the age of five years, however this is a very rare occurrence. During the assembly of most picornaviruses (e.g. poliovirus, rhinovirus and foot-and-mouth disease virus), the capsid precursor protein VP0 is cleaved into VP4 and VP2. However, Kobuviruses retain an uncleaved VP0. From studies with other picornaviruses, it is known that VP4 performs the essential function of pore formation in membranes, which facilitates transfer of the viral genome across the endosomal membrane and into the cytoplasm for replication. Here, we employ genome exposure and membrane interaction assays to demonstrate that pH plays a critical role in AiV uncoating and membrane interactions. We demonstrate that incubation at low pH alters the exposure of hydrophobic residues within the capsid, enhances genome exposure and enhances permeabilisation of model membranes. Furthermore, using peptides we demonstrate that the N-terminus of VP0 mediates membrane pore formation in model membranes, indicating that this plays an analogous function to VP4. Importance: To initiate infection, viruses must enter a host cell and deliver their genome into the appropriate location. The picornavirus family of small non-enveloped RNA viruses includes significant human and animal pathogens and are also models to understand the process of cell entry. Most picornavirus capsids contain the internal protein VP4, generated from cleavage of a VP0 precursor. During entry, VP4 is released from the capsid. In enteroviruses this forms a membrane pore, which facilitates genome release into the cytoplasm. Due to high levels of sequence similarity, it is expected to play the same role for other picornaviruses. Some picornaviruses, such as Aichi virus, retain an intact VP0, and it is unknown how these viruses re-arrange their capsids and induce membrane permeability in the absence of VP4. Here we have used Aichi virus as a model VP0 virus to test for conservation of function between VP0 and VP4. This could enhance understanding of pore function and lead to development of novel therapeutic agents that block entry.

scholarly journals Comparison of the interactions of daunorubicin in a free form and attached to single-walled carbon nanotubes with model lipid membranes

2016 ◽  
Vol 7 ◽  
pp. 524-532 ◽  
Author(s):  
Dorota Matyszewska
Keyword(s):  
Carbon Nanotubes ◽  
Lipid Membranes ◽  
Hydrophobic Interactions ◽  
Drug Carrier ◽  
Surface Concentration ◽  
Free Drug ◽  
Model Membranes ◽  
Free Form ◽  
Comparable Amount ◽  
Model Lipid Membranes

In this work the interactions of an anticancer drug daunorubicin (DNR) with model thiolipid layers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) were investigated using Langmuir technique. The results obtained for a free drug were compared with the results recorded for DNR attached to SWCNTs as potential drug carrier. Langmuir studies of mixed DPPTE–SWCNTs-DNR monolayers showed that even at the highest investigated content of the nanotubes in the monolayer, the changes in the properties of DPPTE model membranes were not as significant as in case of the incorporation of a free drug, which resulted in a significant increase in the area per molecule and fluidization of the thiolipid layer. The presence of SWCNTs-DNR in the DPPTE monolayer at the air–water interface did not change the organization of the lipid molecules to such extent as the free drug, which may be explained by different types of interactions playing crucial role in these two types of systems. In the case of the interactions of free DNR the electrostatic attraction between positively charged drug and negatively charged DPPTE monolayer play the most important role, while in the case of SWCNTs-DNR adducts the hydrophobic interactions between nanotubes and acyl chains of the lipid seem to be prevailing. Electrochemical studies performed for supported model membranes containing the drug delivered in the two investigated forms revealed that the surface concentration of the drug-nanotube adduct in supported monolayers is comparable to the reported surface concentration of the free DNR incorporated into DPPTE monolayers on gold electrodes. Therefore, it may be concluded that the application of carbon nanotubes as potential DNR carrier allows for the incorporation of comparable amount of the drug into model membranes with simultaneous decrease in the negative changes in the membrane structure and organization, which is an important aspect in terms of side effects of the drug.

Consequences of the interaction of calcium with dioleoylphosphatidate-containing model membranes: calcium-membrane and membrane-membrane interactions

1987 ◽  
Vol 897 (1) ◽  
pp. 180-190 ◽  
Author(s):  
Erik B. Smaal ◽  
Jacqueline G. Mandersloot ◽  
Rudy A. Demel ◽  
Ben de Kruijff ◽  
Johannes de Gier
Keyword(s):  
Model Membranes ◽  
Membrane Interactions

scholarly journals Brevinin-2GHk from Sylvirana guentheri and the Design of Truncated Analogs Exhibiting the Enhancement of Antimicrobial Activity

Antibiotics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 85 ◽  
Author(s):  
Guanzhu Chen ◽  
Yuxi Miao ◽  
Chengbang Ma ◽  
Mei Zhou ◽  
Zhanzhong Shi ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Mammalian Cells ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Helical Conformation ◽  
Skin Secretion ◽  
Mature Peptide ◽  
Diverse Range ◽  
Low Cytotoxicity ◽  
Α Helix

Brevinins are an important antimicrobial peptide (AMP) family discovered in the skin secretions of Ranidae frogs. The members demonstrate a typical C-terminal ranabox, as well as a diverse range of other structural characteristics. In this study, we identified a novel brevinin-2 peptide from the skin secretion of Sylvirana guentheri, via cloning transcripts, and identifying the expressed mature peptide, in the skin secretion. The confirmed amino acid sequence of the mature peptide was designated brevinin-2GHk (BR2GK). Moreover, as a previous study had demonstrated that the N-terminus of brevinin-2 is responsible for exerting antimicrobial activity, we also designed a series of truncated derivatives of BR2GK. The results show that the truncated derivatives exhibit significantly improved antimicrobial activity and cytotoxicity compared to the parent peptide, except a Pro14 substituted analog. The circular dichroism (CD) analysis of this analog revealed that it did not fold into a helical conformation in the presence of either lipopolysaccharides (LPS) or TFE, indicating that position 14 is involved in the formation of the α-helix. Furthermore, three more analogs with the substitutions of Ala, Lys and Arg at the position 14, respectively, revealed the influence on the membrane disruption potency on bacteria and mammalian cells by the structural changes at this position. Overall, the N-terminal 25-mer truncates demonstrated the potent antimicrobial activity with low cytotoxicity.

scholarly journals Application of attenuated total reflection infrared spectroscopy in the study ofPeruphasma schulteidefensive secretion

2007 ◽  
Vol 21 (3) ◽  
pp. 169-176 ◽  
Author(s):  
Michael P. Mcleod ◽  
Aaron T. Dossey ◽  
M. Khalique Ahmed
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Natural Product ◽  
Short Communication ◽  
Defensive Secretion ◽  
Structural Characteristics ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Ft Ir ◽  
Ir Study

In this short communication, we present the first Fourier Transform Infrared Absorbance (FT-IR) study of peruphasmal; a defensive secretion fromPeruphasma schultei. The spectral data collected are representative of the natural product structure proposed by Dossey et al. This study demonstrates the viability of FT-IR as another tool in the physical and biological chemist's repertoire for use in determining important structural characteristics from minute amounts of available sample.

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