To date, a number of lantibiotics have been shown to use lipid II-a highly conserved peptidoglycan precursor in the cytoplasmic membrane of bacteria-as their molecular target. The α-component (Lchα) ...of the two-component lantibiotic lichenicidin, previously isolated from the
VK21 strain, seems to contain two putative lipid II binding sites in its
-terminal and
-terminal domains. Using NMR spectroscopy in DPC micelles, we obtained convincing evidence that the
-terminal mersacidin-like site is involved in the interaction with lipid II. These data were confirmed by the MD simulations. The contact area of lipid II includes pyrophosphate and disaccharide residues along with the first isoprene units of bactoprenol. MD also showed the potential for the formation of a stable
-terminal nisin-like complex; however, the conditions necessary for its implementation in vitro remain unknown. Overall, our results clarify the picture of two component lantibiotics mechanism of antimicrobial action.
In plants, lipid trafficking within and inside the cell is carried out by lipid-binding and transfer proteins. Ligands for these proteins are building and signaling lipid molecules, secondary ...metabolites with different biological activities due to which they perform diverse functions in plants. Many different classes of such lipid-binding and transfer proteins have been found, but the most common and represented in plants are lipid transfer proteins (LTPs), pathogenesis-related class 10 (PR-10) proteins, acyl-CoA-binding proteins (ACBPs), and puroindolines (PINs). A low degree of amino acid sequence homology but similar spatial structures containing an internal hydrophobic cavity are common features of these classes of proteins. In this review, we summarize the latest known data on the features of these protein classes with particular focus on their ability to bind and transfer lipid ligands. We analyzed the structural features of these proteins, the diversity of their possible ligands, the key amino acids participating in ligand binding, the currently known mechanisms of ligand binding and transferring, as well as prospects for possible application.
Currently, the spread of fungal infections is becoming an urgent problem. Fungi of the Candida genus are opportunistic microorganisms that cause superficial and life-threatening systemic candidiasis ...in immunocompromised patients. The list of antifungal drugs for the treatment of candidiasis is very limited, while the prevalence of resistant strains is growing rapidly. Therefore, the search for new antimycotics, including those exhibiting immunomodulatory properties, is of great importance. Plenty of natural compounds with antifungal activities may be extremely useful in solving this problem. This review evaluates the features of natural antimicrobial peptides, namely plant defensins as possible prototypes of new anticandidal agents. Plant defensins are important components of the innate immune system, which provides the first line of defense against pathogens. The introduction presents a brief summary regarding pathogenic Candida species, the pathogenesis of candidiasis, and the mechanisms of antimycotic resistance. Then, the structural features of plant defensins, their anticandidal activities, their mechanisms of action on yeast-like fungi, their ability to prevent adhesion and biofilm formation, and their combined action with conventional antimycotics are described. The possible mechanisms of fungal resistance to plant defensins, their cytotoxic activity, and their effectiveness in in vivo experiments are also discussed. In addition, for the first time for plant defensins, knowledge about their immunomodulatory effects is also presented.
Plant lipid transfer proteins (LTPs) are known to be clinically significant allergens capable of binding various lipid ligands. Recent data showed that lipid ligands affected the allergenic ...properties of plant LTPs. In this work, we checked the assumption that specific amino acid residues in the Len c 3 structure can play a key role both in the interaction with lipid ligands and IgE-binding capacity of the allergen. The recombinant analogues of Len c 3 with the single or double substitutions of Thr41, Arg45 and/or Tyr80 were obtained by site-directed mutagenesis. All these amino acid residues are located near the "bottom" entrance to the hydrophobic cavity of Len c 3 and are likely included in the IgE-binding epitope of the allergen. Using a bioinformatic approach, circular dichroism and fluorescence spectroscopies, ELISA, and experiments mimicking the allergen Len c 3 gastroduodenal digestion we showed that the substitution of all the three amino acid residues significantly affected structural organization of this region and led both to a change of the ligand-binding capacity and the allergenic potential of Len c 3.
A novel synergetic lantibiotic pair, Lchα (3249.51 Da) and Lchβ (3019.36 Da), termed lichenicidin VK21, was isolated from the producer strain Bacillus licheniformis VK21. Chemical and spatial ...structures of Lchα and Lchβ were determined. Each peptide contains 31 amino acid residues linked by 4 intramolecular thioether bridges and the N-terminal 2-oxobutyryl group. Spatial structures of Lchα and Lchβ were studied by NMR spectroscopy in methanol solution. The Lchα peptide displays structural homology with mersacidin-like lantibiotics and involves relatively well-structured N- and C-terminal domains connected by a flexible loop stabilized by a thioether bridge Ala11-S-Ala21. In contrast, the Lchβ peptide represents a prolonged hydrophobic α-helix flanked with more flexible N- and C-terminal domains. A lantibiotic cluster of the Bacillus licheniformis VK21 genome which comprises the structural genes, lchA1 and lchA2, encoding the lantibiotics precursors, as well as the gene of a modifying enzyme lchM1, was amplified and sequenced. The mature peptides, Lchα and Lchβ, interact synergistically to possess antibiotic activity against Gram-positive bacteria within a nanomolar concentration range, though the individual peptides were shown to be active at micromolar concentrations. Our results afford molecular insight into the mechanism of lichenicidin VK21 action.
A novel 40-residue antimicrobial peptide, aurelin, exhibiting activity against Gram-positive and Gram-negative bacteria, was purified from the mesoglea of a scyphoid jellyfish
Aurelia aurita by ...preparative gel electrophoresis and RP-HPLC. Molecular mass (4296.95
Da) and complete amino acid sequence of aurelin (AACSDRAHGHICESFKSFCKDSGRNGVKLRANCKKTCGLC)
1
The protein sequence data reported in this paper will appear in the UniProt Knowledge base under the Accession No.
P84891 and in the GenBank under the Accession No.
DQ837210.
1
were determined. Aurelin has six cysteines forming three disulfide bonds. The total RNA was isolated from the jellyfish mesoglea, RT-PCR and cloning were performed, and cDNA was sequenced. A 84-residue preproaurelin contains a putative signal peptide (22 amino acids) and a propiece of the same size (22 amino acids). Aurelin has no structural homology with any previously identified antimicrobial peptides but reveals partial similarity both with defensins and K
+ channel-blocking toxins of sea anemones and belongs to ShKT domain family.
Two novel 21-residue antimicrobial peptides, arenicin-1 and arenicin-2, exhibiting activity against Gram-positive and Gram-negative bacteria and fungi, were purified from coelomocytes of marine ...polychaeta
Arenicola marina (lugworm) by preparative gel electrophoresis and RP-HPLC. Molecular masses (2758.3 and 2772.3 Da) and complete amino acid sequences (RWCVYAYVRVRGVLVRYRRCW and RWCVYAYVRIRGVLVRYRRCW)
1
The protein sequence data reported in this paper will appear in the Swiss-Prot and TrEMBL knowledgebase under the accession numbers P84105 for arenicin-1 and P84106 for arenicin-2.
1
were determined for each isoform. Each arenicin has one disulfide bond (Cys3-Cys20). The total RNA was isolated from the lugworm coelomocytes, RT-PCR and cloning were performed, and cDNA was sequenced. A 202-residue preproarenicin contains a putative signal peptide (25 amino acids) and a long prodomain. Arenicins have no structure similarity to any previously identified antimicrobial peptides.
A novel defensin from the lentil Lens culinaris seeds Finkina, Ekaterina I.; Shramova, Elena I.; Tagaev, Andrey A. ...
Biochemical and biophysical research communications,
07/2008, Letnik:
371, Številka:
4
Journal Article
Recenzirano
A novel 47-residue plant defensin was purified from germinated seeds of the lentil
Lens culinaris by ammonium sulfate precipitation, gel filtration, chromatography, and RP-HPLC. The molecular mass ...(5440.41
Da) and complete amino acid sequence (KTCENLSDSFKGPCIPDGNCNKHCKEKEHLLSGRCRDDFRCWCTRNC)
1
The protein sequence data reported in this paper will appear in the UniProt Knowledgebase under the Accession No.
P85530 and in the GenBank under the accession number
EF194158.
1
of defensin, termed Lc-def, were determined. Lc-def has eight cysteines forming four disulfide bonds. The total RNA was isolated from lentil germinated seeds, RT-PCR and subsequent cloning were performed, and cDNA was sequenced. A 74-residue predefensin contains a putative signal peptide (27 amino acid) and a mature protein. Lc-def shows high sequence homology with legumes defensins, exhibits an activity against
Aspergillus niger, but does not inhibit proteolytic enzymes.
Antiamoebin I (Aam‐I) is a membrane‐active peptaibol antibiotic isolated from fungal species belonging to the genera Cephalosporium, Emericellopsis, Gliocladium, and Stilbella. In comparison with ...other 16‐amino acid‐residue peptaibols, e.g., zervamicin IIB (Zrv‐IIB), Aam‐I possesses relatively weak biological and channel‐forming activities. In MeOH solution, Aam‐I demonstrates fast cooperative transitions between right‐handed and left‐handed helical conformation of the N‐terminal (1–8) region. We studied Aam‐I spatial structure and backbone dynamics in the membrane‐mimicking environment (DMPC/DHPC bicelles)1) by heteronuclear 1H,13C,15N‐NMR spectroscopy. Interaction with the bicelles stabilizes the Aam‐I right‐handed helical conformation retaining significant intramolecular mobility on the ms–μs time scale. Extensive ms–μs dynamics were also detected in the DPC and DHPC micelles and DOPG nanodiscs. In contrast, Zrv‐IIB in the DPC micelles demonstrates appreciably lesser mobility on the μs–ms time scale. Titration with Mn2+ and 16‐doxylstearate paramagnetic probes revealed Aam‐I binding to the bicelle surface with the N‐terminus slightly immersed into hydrocarbon region. Fluctuations of the Aam‐I helix between surface‐bound and transmembrane (TM) state were observed in the nanodisc membranes formed from the short‐chain (diC12 : 0) DLPC/DLPG lipids. All the obtained experimental data are in agreement with the barrel‐stave model of TM pore formation, similarly to the mechanism proposed for Zrv‐IIB and other peptaibols. The observed extensive intramolecular dynamics explains the relatively low activity of Aam‐I.
Zervamicins IIA and IIB are members of the peptaibol family of peptide antibiotics. They are produced by the fungus Emericellopsis salmosynnemata. Peptaibols are known to be of potential usefulness ...for chemotherapeutic applications, as are other secondary fungal metabolites. Previously, we have found zervamicins to decrease spontaneous locomotor activity in mice, suggesting their neurotropic properties on an equal footing with antimicrobial activity. The current study deals with behavioral effects of zervamicins IIA and IIB in mice. According to our results, both zervamicins induce a reliable decrease in locomotion and exploratory activity measured in the hole‐board test. The behavioral effects of zervamicin IIA become apparent at lower dosages (0.05–2.0 mg/kg) as compared with zervamicin IIB (0.5–12.0 mg/kg). The experiments on behavioral effects in the elevated plus maze test showed that both zervamicins caused a reliable decrease in the number of head‐dippings, open‐arm entries, and rearings. The observed behavioral effects may be rather associated with a decrease in the exploratory activity than with anxiety‐related responses in mice. Zervamicins induced depression‐like behavior of experimental animals in the forced‐swim test. Both peptaibols reduce physical endurance and change motor coordination of experimental animals in the bar‐holding test. Taken together, the data obtained clearly indicate that both zervamicins possess neuroleptic activity.
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