The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform
Marina Rautenbach - One of the best experts on this subject based on the ideXlab platform.
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oligomerisation of tryptocidine c a trp rich cyclodecapeptide from the antimicrobial Tyrothricin complex
Biochimie, 2021Co-Authors: Marina Rautenbach, Arnold J Vosloo, Vikas Kumar, Yasamin Masoudi, Rosalind J Van Wyk, Marietjie StanderAbstract:Abstract Tryptocidine C (TpcC, cyclo[D-Phe1-Pro2-Trp3-D-Trp4-Asn5-Gln6-Trp7-Val8-Orn9-Leu10]) is a broad-spectrum antimicrobial peptide in the Tyrothricin complex produced by a soil bacterium, Brevibacillus parabrevis. Electrospray mass spectrometric studies reveal the oligomerisation of TpcC into dimers and higher oligomers, analogous to tyrocidine C (TrcC, Trp7 replaced by Tyr7). Ion mobility mass spectrometry (IMMS) further confirms the formation of stable peptide dimers and tetramers with diameters of 2.7 nm and 3.3 nm, respectively, calculated from collisional cross section (CCS). Molecular dynamic simulations and docking studies support the formation of amphipathic dimers, with a diameter of 2.5 ± 0.07 nm calculated from low energy model CCS. Circular dichroism and IMMS studies point towards dynamic hydrogen-bonded conformational changes up to 28–33 μM after which the structures become more static (or in equilibrium). Fluorescence studies indicate aromatic stacking of Trp residues with a CMC of 18 μM in aqueous solutions. The concentration and time dependent interaction of Trp in oligomers indicate cooperativity in the TpcC oligomerisation that leads to the formation of higher order microscopic structures. Scanning electron microscopy studies unequivocally shows that TpcC forms nanospheres with a mean diameter of 25 nm. Repeated smaller oligomeric units, possibly dimers and tetramers, self-assemble to form these nanospheres.
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following Tyrothricin peptide production by brevibacillus parabrevis with electrospray mass spectrometry
Biochimie, 2020Co-Authors: Arnold J Vosloo, Marina RautenbachAbstract:Abstract The tyrocidines and analogues are cationic cyclodecapeptides [cyclo (D-Phe1-L-Pro2-L-(Phe3/Trp3)-D-(Phe4/Trp4)-L-Asn5-L-Gln6-L-(Tyr7/Phe7/Trp7)-L-Val8-L-(Orn9/Lys9)-L-Leu10], produced together with the neutral linear pentadecapeptide gramicidins, in the antibiotic Tyrothricin complex by Brevibacillus parabrevis. Despite discovery 80 years ago, it was still uncertain whether these peptides are secreted or sequestered intracellularly. We resolved this by utilising high resolution electrospray mass spectrometry to confirm the predominantly intracellular sequestration of the peptides in the Tyrothricin complex. A “peptidomics” approach allowed us to map the intracellular production of 16 cyclodecapeptides and 6 gramicidins over 16 days of culturing. Gramicidin production remained relatively constant, with Val-gramicidin A the predominant analogue produced throughout the 16 day fermentation period. The Tyrothricin cyclodecapeptides have four variable positions and there was a culturing time related shift from the Phe-rich A analogues, containing a L-Phe3-D-Phe4 aromatic dipeptide unit, to the Trp-rich C analogues with L-Trp3-D-Trp4. For the other variable aromatic residue position, Tyr7 was preferentially incorporated above Trp7, with a minor incorporation of Phe7 over the whole culturing period. For the variable basic amino acid residue, there was time-sensitive shift from Orn9 to Lys9 incorporation. Modulation of the cyclodecapeptide profile over time does not correlate with the reported non-ribosomal peptide synthetase affinity, specifically for Trp in the variable aromatic residue positions, indicating additional supply-demand control in the cyclodecapeptides production by B. parabrevis. These novel observations are not only of importance for production and purification of selected peptide analogues from the Tyrothricin complex, but also for insight into microbial control of non-ribosomal peptide production that extends beyond the peptide synthetase machinery.
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Tolerance of honey bee adults and larvae toward Tyrothricin peptides derived from Brevibacillus parabrevis
Apidologie, 2017Co-Authors: J. Arnold Vosloo, Hannes Beims, Michael H. Allsopp, Wilma Rensburg, Werner Ohe, Michael Steinert, Marina RautenbachAbstract:Tyrothricin is a peptide complex containing the linear gramicidins and cyclic tyrocidines. The tyrocidines have potent activity against fungal plant pathogens. As these peptides have possible agricultural applications, their toxicity was evaluated toward honey bee adults and larvae. Tyrothricin formulated in sucrose was non-toxic to caged adult honey bees at up to 1.5 g/L over 48-h exposure, which is 100- to 200-fold higher than the amount needed to eradicate high fungal loads (2 × 10^4 spores/mL). Moreover, Tyrothricin and the tyrocidines displayed potent in vitro activity toward foulbrood causing pathogens ( Paenibacillus larvae , Melissococcus plutonius , Paenibacillus alvei ) in honey bee larvae. In vivo Tyrothricin or tyrocidine treatment delayed infection onset, indicating potential for curing. Tyrothricin was also found to be non-toxic with possible protective action in a semi-field trial on young bees released into hives, indicating the relative safety of the application of these antimicrobial peptides in an agricultural setting.
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manipulation of the Tyrothricin production profile of bacillus aneurinolyticus
Microbiology, 2013Co-Authors: Johan Arnold Vosloo, Marietjie Stander, Adrienne Nyangonkeh Leussa, Barbara M Spathelf, Marina RautenbachAbstract:A group of non-ribosomally produced antimicrobial peptides, the tyrocidines from the Tyrothricin complex, have potential as antimicrobial agents in both medicine and industry. Previous work by our group illustrated that the more polar tyrocidines rich in Trp residues in their structure were more active toward Gram-positive bacteria, while the more non-polar tyrocidines rich in Phe residues had greater activity toward Plasmodium falciparum, one of the major causative pathogens of malaria in humans. Our group also found that the tyrocidines have pronounced antifungal activity, dictated by the primary sequence of the tyrocidine. By simply manipulating the Phe or Trp concentration in the culture medium of the Tyrothricin producer, Bacillus aneurinolyticus ATCC 10068, we were able to modulate the production of subsets of tyrocidines, thereby tailoring the Tyrothricin complex to target specific pathogens. We optimized the tailored Tyrothricin production using a novel, small-scale, high-throughput deep 96-well plate culturing method followed by analyses of the peptide mixtures using ultra-performance liquid chromatography linked to mass spectrometry. We were able to gradually shift the production profile of the tyrocidines and analogues, as well as the gramicidins between two extremes in terms of peptide subsets and peptide hydrophobicity. This study demonstrated that Tyrothricin peptide subsets with targeted activity can be efficiently produced by simple manipulation of the aromatic amino acid profile of the culture medium.
Ulrike Blumepeytavi - One of the best experts on this subject based on the ideXlab platform.
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reduction of inflammatory and noninflammatory lesions with topical Tyrothricin 0 1 in the treatment of mild to severe acne papulopustulosa a randomized controlled clinical trial
Skin Pharmacology and Physiology, 2016Co-Authors: Claudia Richter, Carina Trojahn, Kathrin Hillmann, G Dobos, Andrea Stroux, Jan Kottner, Ulrike BlumepeytaviAbstract:Background/Aims: Antibiotic-induced drug resistance requires new approaches in topical acne treatment. Tyrothricin is known to produce no resistance. In this stud
Miguel Valcárcel - One of the best experts on this subject based on the ideXlab platform.
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Development and validation of chromatographic methods (HPLC and GC) for the determination of the active components (benzocaine, Tyrothricin and menthol) of a pharmaceutical preparation
Journal of pharmaceutical and biomedical analysis, 1995Co-Authors: F. Ortiz-boyer, María Teresa Tena, M. D. Luque De Castro, Miguel ValcárcelAbstract:Methods are reported for the determination of Tyrothricin and benzocaine by HPLC and menthol by GC in the analysis of throat lozenges (tablets) containing all three compounds. After optimization of the variables involved in both HPLC and GC the methods have been characterized and validated according to the guidelines of the Spanish Pharmacopoeia, and applied to both the monitoring of the manufacturing process and the quality control of the final product.
Arnold J Vosloo - One of the best experts on this subject based on the ideXlab platform.
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oligomerisation of tryptocidine c a trp rich cyclodecapeptide from the antimicrobial Tyrothricin complex
Biochimie, 2021Co-Authors: Marina Rautenbach, Arnold J Vosloo, Vikas Kumar, Yasamin Masoudi, Rosalind J Van Wyk, Marietjie StanderAbstract:Abstract Tryptocidine C (TpcC, cyclo[D-Phe1-Pro2-Trp3-D-Trp4-Asn5-Gln6-Trp7-Val8-Orn9-Leu10]) is a broad-spectrum antimicrobial peptide in the Tyrothricin complex produced by a soil bacterium, Brevibacillus parabrevis. Electrospray mass spectrometric studies reveal the oligomerisation of TpcC into dimers and higher oligomers, analogous to tyrocidine C (TrcC, Trp7 replaced by Tyr7). Ion mobility mass spectrometry (IMMS) further confirms the formation of stable peptide dimers and tetramers with diameters of 2.7 nm and 3.3 nm, respectively, calculated from collisional cross section (CCS). Molecular dynamic simulations and docking studies support the formation of amphipathic dimers, with a diameter of 2.5 ± 0.07 nm calculated from low energy model CCS. Circular dichroism and IMMS studies point towards dynamic hydrogen-bonded conformational changes up to 28–33 μM after which the structures become more static (or in equilibrium). Fluorescence studies indicate aromatic stacking of Trp residues with a CMC of 18 μM in aqueous solutions. The concentration and time dependent interaction of Trp in oligomers indicate cooperativity in the TpcC oligomerisation that leads to the formation of higher order microscopic structures. Scanning electron microscopy studies unequivocally shows that TpcC forms nanospheres with a mean diameter of 25 nm. Repeated smaller oligomeric units, possibly dimers and tetramers, self-assemble to form these nanospheres.
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following Tyrothricin peptide production by brevibacillus parabrevis with electrospray mass spectrometry
Biochimie, 2020Co-Authors: Arnold J Vosloo, Marina RautenbachAbstract:Abstract The tyrocidines and analogues are cationic cyclodecapeptides [cyclo (D-Phe1-L-Pro2-L-(Phe3/Trp3)-D-(Phe4/Trp4)-L-Asn5-L-Gln6-L-(Tyr7/Phe7/Trp7)-L-Val8-L-(Orn9/Lys9)-L-Leu10], produced together with the neutral linear pentadecapeptide gramicidins, in the antibiotic Tyrothricin complex by Brevibacillus parabrevis. Despite discovery 80 years ago, it was still uncertain whether these peptides are secreted or sequestered intracellularly. We resolved this by utilising high resolution electrospray mass spectrometry to confirm the predominantly intracellular sequestration of the peptides in the Tyrothricin complex. A “peptidomics” approach allowed us to map the intracellular production of 16 cyclodecapeptides and 6 gramicidins over 16 days of culturing. Gramicidin production remained relatively constant, with Val-gramicidin A the predominant analogue produced throughout the 16 day fermentation period. The Tyrothricin cyclodecapeptides have four variable positions and there was a culturing time related shift from the Phe-rich A analogues, containing a L-Phe3-D-Phe4 aromatic dipeptide unit, to the Trp-rich C analogues with L-Trp3-D-Trp4. For the other variable aromatic residue position, Tyr7 was preferentially incorporated above Trp7, with a minor incorporation of Phe7 over the whole culturing period. For the variable basic amino acid residue, there was time-sensitive shift from Orn9 to Lys9 incorporation. Modulation of the cyclodecapeptide profile over time does not correlate with the reported non-ribosomal peptide synthetase affinity, specifically for Trp in the variable aromatic residue positions, indicating additional supply-demand control in the cyclodecapeptides production by B. parabrevis. These novel observations are not only of importance for production and purification of selected peptide analogues from the Tyrothricin complex, but also for insight into microbial control of non-ribosomal peptide production that extends beyond the peptide synthetase machinery.
Claudia Richter - One of the best experts on this subject based on the ideXlab platform.
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reduction of inflammatory and noninflammatory lesions with topical Tyrothricin 0 1 in the treatment of mild to severe acne papulopustulosa a randomized controlled clinical trial
Skin Pharmacology and Physiology, 2016Co-Authors: Claudia Richter, Carina Trojahn, Kathrin Hillmann, G Dobos, Andrea Stroux, Jan Kottner, Ulrike BlumepeytaviAbstract:Background/Aims: Antibiotic-induced drug resistance requires new approaches in topical acne treatment. Tyrothricin is known to produce no resistance. In this stud
