The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
David J. Craik - One of the best experts on this subject based on the ideXlab platform.
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Efficient Enzymatic Cyclization of Disulfide-Rich Peptides by Using Peptide Ligases.
Chembiochem : a European journal of chemical biology, 2019Co-Authors: Marcel Schmidt, David J. Craik, Yen-hua Huang, Eduardo F. Texeira De Oliveira, Ana Toplak, Hein J. Wijma, Dick B. Janssen, Jan H. Van Maarseveen, Timo NuijensAbstract:Disulfide-rich macrocyclic peptides-cyclotides, for example-represent a promising class of molecules with potential therapeutic use. Despite their potential their efficient synthesis at large scale still represents a major challenge. Here we report new chemoenzymatic strategies using peptide ligase variants-inter alia, omniligase-1-for the efficient and scalable one-pot cyclization and folding of the native cyclotides MCoTI-II, kalata B1 and variants thereof, as well as of the Theta-Defensin RTD-1. The synthesis of the kB1 variant T20K was successfully demonstrated at multi-gram scale. The existence of several ligation sites for each macrocycle makes this approach highly flexible and facilitates both the larger-scale manufacture and the engineering of bioactive, grafted cyclotide variants, therefore clearly offering a valuable and powerful extension of the existing toolbox of enzymes for peptide head-to-tail cyclization.
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Constrained cyclic peptides as immunomodulatory inhibitors of the CD2:CD58 protein-protein interaction
ACS chemical biology, 2016Co-Authors: Rushikesh Sable, David J. Craik, Thomas Durek, Veena Taneja, Sandeep Pallerla, Ted J. Gauthier, Seetharama D. JoisAbstract:The interaction between the cell–cell adhesion proteins CD2 and CD58 plays a crucial role in lymphocyte recruitment to inflammatory sites, and inhibitors of this interaction have potential as immunomodulatory drugs in autoimmune diseases. Peptides from the CD2 adhesion domain were designed to inhibit CD2:CD58 interactions. To improve the stability of the peptides, β-sheet epitopes from the CD2 region implicated in CD58 recognition were grafted into the cyclic peptide frameworks of sunflower trypsin inhibitor and rhesus Theta Defensin. The designed multicyclic peptides were evaluated for their ability to modulate cell–cell interactions in three different cell adhesion assays, with one candidate, SFTI-a, showing potent activity in the nanomolar range (IC50: 51 nM). This peptide also suppresses the immune responses in T cells obtained from mice that exhibit the autoimmune disease rheumatoid arthritis. SFTI-a was resistant to thermal denaturation, as judged by circular dichroism spectroscopy and mass spectrom...
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Insights into the Molecular Flexibility of θ-Defensins by NMR Relaxation Analysis
The journal of physical chemistry. B, 2014Co-Authors: Anne C. Conibear, K. Johan Rosengren, Conan K. Wang, Julio A. Camarero, David J. CraikAbstract:Theta-Defensins are mammalian cyclic peptides that have antimicrobial activity and show potential as stable scaffolds for peptide-based drug design. The cyclic cystine ladder structural motif of ?-Defensins has been characterized using NMR spectroscopy and is important for their structure and stability. However, the effect of the pronounced elongated topology of Theta-Defensins on their molecular motion is not yet understood. Studies of molecular motion by NMR relaxation measurements have been facilitated by the recent development of a semirecombinant method for producing cyclic peptides that allows for isotopic labeling. Here we have undertaken a multifield N-15 NMR relaxation analysis of the anti-HIV Theta-Defensin, HTD-2, and interpreted the experimental data using various models of overall and internal molecular motion. We found that it was necessary to apply a model that includes internal motion to account for the variations in the experimental T-1 and NOE data at different backbone amide sites in the peptide. Although an isotropic model with internal motion was the simplest model that provided a satisfactory fit with the experimental data, we cannot exclude the possibility that overall motion is anisotropic, especially considering the strikingly elongated topology of Theta-Defensins. The presence of flexible side chains, self-association, interactions with solvent, and internal motions are all potential contributors to the observed relaxation data. Internal motion consistent with the constraints imposed by the cyclic cystine ladder was observed in that the order parameters, S-2, show that residues in the turns are more flexible than those in the beta-sheet. This study provides insights into the dynamics of Theta-Defensins and information that might be useful in their application as scaffolds in drug design.
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The Cyclic Cystine Ladder of Theta-Defensins as a Stable, Bifunctional Scaffold: A Proof-of-Concept Study Using the Integrin-Binding RGD Motif.
Chembiochem : a European journal of chemical biology, 2014Co-Authors: Anne C. Conibear, K. Johan Rosengren, Alexander Bochen, Petar Stupar, Conan K. Wang, Horst Kessler, David J. CraikAbstract:Peptides have the specificity and size required to target the protein-protein interactions involved in many diseases. Some cyclic peptides have been utilised as scaffolds for peptide drugs because of their stability; however, other cyclic peptide scaffolds remain to be explored. Theta-Defensins are cyclic peptides from mammals; they are characterised by a cyclic cystine ladder motif and have low haemolytic and cytotoxic activity. Here we demonstrate the potential of the cyclic cystine ladder as a scaffold for peptide drug design by introducing the integrin-binding Arg-Gly-Asp (RGD) motif into the Theta-Defensin RTD-1. The most active analogue had an IC50 of 18 nm for the alpha(v)beta(3) integrin as well as high serum stability, thus demonstrating that a desired bioactivity can be imparted to the cyclic cystine ladder. This study highlights how Theta-Defensins can provide a stable and conformationally restrained scaffold for bioactive epitopes in a beta-strand or turn conformation. Furthermore, the symmetry of the cyclic cystine ladder presents the opportunity to design peptides with dual bioactive epitopes to increase activity and specificity.
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Retrocyclin-2: a potent anti-HIV Theta-Defensin that forms a cyclic cystine ladder structural motif.
Advances in experimental medicine and biology, 2009Co-Authors: Norelle L. Daly, Robert I. Lehrer, Yi-kuang Chen, K. Johan Rosengren, Ute C. Marx, Martin L. Phillips, Alan J. Waring, Wei Wang, David J. CraikAbstract:Retrocyclin-2: a potent anti-HIV Theta-Defensin that forms a cyclic cysteine ladder structural motif
Michael E. Selsted - One of the best experts on this subject based on the ideXlab platform.
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RTD-1 therapeutically normalizes synovial gene signatures in rat autoimmune arthritis and suppresses proinflammatory mediators in RA synovial fibroblasts.
Physiological genomics, 2019Co-Authors: Prasad Tongaonkar, Justin B. Schaal, Dat Tran, Vasu Punj, Akshay Subramanian, Katie K. Trinh, Teresina Laragione, Andre J. Ouellette, Pércio S. Gulko, Michael E. SelstedAbstract:Rhesus Theta Defensin-1 (RTD-1), a macrocyclic immunomodulatory host defense peptide from Old World monkeys, is therapeutic in pristane-induced arthritis (PIA) in rats, a model of rheumatoid arthri...
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Rhesus Theta-Defensin Prevents Death in a Mouse Model of Severe Acute Respiratory Syndrome Coronavirus Pulmonary Disease
Journal of virology, 2009Co-Authors: Christine L. Wohlford-lenane, David K. Meyerholz, Stanley Perlman, Haixia Zhou, Dat Q. Tran, Michael E. Selsted, Paul B. MccrayAbstract:We evaluated the efficacy of rhesus Theta-Defensin 1 (RTD-1), a novel cyclic antimicrobial peptide, as a prophylactic antiviral in a mouse model of severe acute respiratory syndrome (SARS) coronavirus (CoV) lung disease. BALB/c mice exposed to a mouse-adapted strain of SARS-CoV demonstrated 100% survival and modest reductions in lung pathology without reductions in virus titer when treated with two intranasal doses of RTD-1, while mortality in untreated mice was ∼75%. RTD-1-treated, SARS-CoV-infected mice displayed altered lung tissue cytokine responses 2 and 4 days postinfection compared to those of untreated animals, suggesting that one possible mechanism of action for RTD-1 is immunomodulatory.
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Theta-Defensins: cyclic antimicrobial peptides produced by binary ligation of truncated alpha-Defensins.
Current protein & peptide science, 2004Co-Authors: Michael E. SelstedAbstract:The first cyclic peptide discovered in animals is an antimicrobial octadecapeptide that is expressed in leukocytes of rhesus monkeys. The peptide, termed rhesus Theta-Defensin 1 (RTD-1) is the prototype of a new family of antimicrobial peptides, which like the previously characterized alpha- and beta-Defensin families, possesses broad spectrum microbicidal activities against bacteria, fungi, and protects mononuclear cells from infection by HIV-1. The cyclic Theta-Defensin structure is essential for a number of its antimicrobial properties, as demonstrated by the markedly reduced microbicidal activities of de-cyclized Theta-Defensin analogs. Genetic and biochemical experiments disclosed that the biosynthesis of RTD-1 results from the head-to-tail joining of two nine-amino acid peptides, each of which is donated by a separate precursor polypeptide, which are in fact C-terminally truncated pro-alpha-Defensins. Alternate combinations of the two nonapeptides generate two additional macaque Theta-Defensins, RTD-2 and RTD-3. Humans do not express Theta-Defensin peptides, but mRNAs encoding at least two Theta-Defensins are expressed in human bone marrow. However, in each case the open reading frame is interrupted by a stop codon in the signal peptide-coding region. The mature Theta-Defensin peptide is a two-stranded beta-sheet that, like the alpha- and beta-Defensins, is stabilized by three disulfides. However, the parallel orientation of the Theta-Defensin disulfide arrangement allows for substantial flexibility around its short axis. Unlike alpha- and beta-Defensins, RTD-1 lacks an amphiphilic topology. This may partially explain the unusual interaction between Theta-Defensins and phospholipid bilayers.
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a cyclic antimicrobial peptide produced in primate leukocytes by the ligation of two truncated α Defensins
Science, 1999Co-Authors: Yiqua Tang, Andre J. Ouellette, Ju Yua, George Osapay, Klara Osapay, Da Q Tra, Christophe J Mille, Michael E. SelstedAbstract:Analysis of rhesus macaque leukocytes disclosed the presence of an 18-residue macrocyclic, tridisulfide antibiotic peptide in granules of neutrophils and monocytes. The peptide, termed rhesus Theta Defensin-1 (RTD-1), is microbicidal for bacteria and fungi at low micromolar concentrations. Antibacterial activity of the cyclic peptide was threefold greater than that of an open-chain analog, and the cyclic conformation was required for antimicrobial activity in the presence of 150 millimolar sodium chloride. Biosynthesis of RTD-1 involves the head-to-tail ligation of two α-Defensin–related nonapeptides, requiring the formation of two new peptide bonds. Thus, host defense cells possess mechanisms for synthesis and granular packaging of macrocyclic antibiotic peptides that are components of the phagocyte antimicrobial armamentarium.
Adam Lesner - One of the best experts on this subject based on the ideXlab platform.
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simplified serine rich Theta Defensin analogues as antitumour peptides
Chemical Biology & Drug Design, 2017Co-Authors: Paulina Strzelecka, Dominika Czaplinska, Rafal Sadej, Anna Wardowska, Michal Pikula, Adam LesnerAbstract:θ-Defensins belong to the family of host defence peptides. They are the only known example of cyclic polypeptides in animal proteomes. This study presents the synthesis of simplified θ-Defensin analogues with pairs of cysteine replaced either by alanine, leucine or serine residues. Cytotoxicity tests were performed on human mammary epithelial (HB2) and breast cancer (SKBR3, MDA-MB-231) cell lines to determine whether peptides are selectively targeting cancer cells. The effect of these peptides was also evaluated in 3D Matrigel cultures, which are based on extracellular matrix components and therefore closely represent in vivo conditions. Finally, to determine whether analogues are able to sensitize MDA-MB-231 triple-negative breast cancer cells to chemotherapeutics, we co-administrated peptides with cisplatin or doxorubicin hydrochloride also in 3D Matrigel cultures. Additionally, cytotoxicity towards peripheral blood mononuclear cells and haemolytic effect were examined for a chosen representative of synthesized compounds. The results showed that positively charged serine-containing θ-Defensin derivatives were more cytotoxic towards breast cancer cells (SKBR3, MDA-MB-231) than towards mammary epithelial cells (HB2). Analogues enhanced the effect of cisplatin and doxorubicin hydrochloride on triple-negative breast cancer cell line (MDA-MB-231).
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Simplified, serine‐rich Theta‐Defensin analogues as antitumour peptides
Chemical biology & drug design, 2017Co-Authors: Paulina Strzelecka, Dominika Czaplinska, Rafal Sadej, Anna Wardowska, Michał Pikuła, Adam LesnerAbstract:θ-Defensins belong to the family of host defence peptides. They are the only known example of cyclic polypeptides in animal proteomes. This study presents the synthesis of simplified θ-Defensin analogues with pairs of cysteine replaced either by alanine, leucine or serine residues. Cytotoxicity tests were performed on human mammary epithelial (HB2) and breast cancer (SKBR3, MDA-MB-231) cell lines to determine whether peptides are selectively targeting cancer cells. The effect of these peptides was also evaluated in 3D Matrigel cultures, which are based on extracellular matrix components and therefore closely represent in vivo conditions. Finally, to determine whether analogues are able to sensitize MDA-MB-231 triple-negative breast cancer cells to chemotherapeutics, we co-administrated peptides with cisplatin or doxorubicin hydrochloride also in 3D Matrigel cultures. Additionally, cytotoxicity towards peripheral blood mononuclear cells and haemolytic effect were examined for a chosen representative of synthesized compounds. The results showed that positively charged serine-containing θ-Defensin derivatives were more cytotoxic towards breast cancer cells (SKBR3, MDA-MB-231) than towards mammary epithelial cells (HB2). Analogues enhanced the effect of cisplatin and doxorubicin hydrochloride on triple-negative breast cancer cell line (MDA-MB-231).
Paul B. Mccray - One of the best experts on this subject based on the ideXlab platform.
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Rhesus Theta-Defensin Prevents Death in a Mouse Model of Severe Acute Respiratory Syndrome Coronavirus Pulmonary Disease
Journal of virology, 2009Co-Authors: Christine L. Wohlford-lenane, David K. Meyerholz, Stanley Perlman, Haixia Zhou, Dat Q. Tran, Michael E. Selsted, Paul B. MccrayAbstract:We evaluated the efficacy of rhesus Theta-Defensin 1 (RTD-1), a novel cyclic antimicrobial peptide, as a prophylactic antiviral in a mouse model of severe acute respiratory syndrome (SARS) coronavirus (CoV) lung disease. BALB/c mice exposed to a mouse-adapted strain of SARS-CoV demonstrated 100% survival and modest reductions in lung pathology without reductions in virus titer when treated with two intranasal doses of RTD-1, while mortality in untreated mice was ∼75%. RTD-1-treated, SARS-CoV-infected mice displayed altered lung tissue cytokine responses 2 and 4 days postinfection compared to those of untreated animals, suggesting that one possible mechanism of action for RTD-1 is immunomodulatory.
Dat Q. Tran - One of the best experts on this subject based on the ideXlab platform.
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Rhesus Theta Defensin 1 Promotes Long Term Survival in Systemic Candidiasis by Host Directed Mechanisms
Scientific Reports, 2019Co-Authors: Virginia Basso, Justin B. Schaal, Dat Q. Tran, Paul M. Beringer, Patti Tran, Yoshihiro Eriguchi, Diana Ngole, Anthony E. Cabebe, A. Young Park, Andre J. OuelletteAbstract:Invasive candidiasis is an increasingly frequent cause of serious and often fatal infections in hospitalized and immunosuppressed patients. Mortality rates associated with these infections have risen sharply due to the emergence of multidrug resistant (MDR) strains of C . albicans and other Candida spp., highlighting the urgent need of new antifungal therapies. Rhesus Theta (θ) Defensin-1 (RTD-1), a natural macrocyclic antimicrobial peptide, was recently shown to be rapidly fungicidal against clinical isolates of MDR C . albicans in vitro . Here we found that RTD-1 was rapidly fungicidal against blastospores of fluconazole/caspofungin resistant C . albicans strains, and was active against established C . albicans biofilms in vitro . In vivo , systemic administration of RTD-1, initiated at the time of infection or 24 h post-infection, promoted long term survival in candidemic mice whether infected with drug-sensitive or MDR strains of C . albicans . RTD-1 induced an early (4 h post treatment) increase in neutrophils in naive and infected mice. In vivo efficacy was associated with fungal clearance, restoration of dysregulated inflammatory cytokines including TNF-α, IL-1β, IL-6, IL-10, and IL-17, and homeostatic reduction in numbers of circulating neutrophils and monocytes. Because these effects occurred using peptide doses that produced maximal plasma concentrations (Cmax) of less than 1% of RTD-1 levels required for in vitro antifungal activity in 50% mouse serum, while inducing a transient neutrophilia, we suggest that RTD-1 mediates its antifungal effects in vivo by host directed mechanisms rather than direct fungicidal activity. Results of this study suggest that θ-Defensins represent a new class of host-directed compounds for treatment of disseminated candidiasis.
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Rhesus Theta-Defensin Prevents Death in a Mouse Model of Severe Acute Respiratory Syndrome Coronavirus Pulmonary Disease
Journal of virology, 2009Co-Authors: Christine L. Wohlford-lenane, David K. Meyerholz, Stanley Perlman, Haixia Zhou, Dat Q. Tran, Michael E. Selsted, Paul B. MccrayAbstract:We evaluated the efficacy of rhesus Theta-Defensin 1 (RTD-1), a novel cyclic antimicrobial peptide, as a prophylactic antiviral in a mouse model of severe acute respiratory syndrome (SARS) coronavirus (CoV) lung disease. BALB/c mice exposed to a mouse-adapted strain of SARS-CoV demonstrated 100% survival and modest reductions in lung pathology without reductions in virus titer when treated with two intranasal doses of RTD-1, while mortality in untreated mice was ∼75%. RTD-1-treated, SARS-CoV-infected mice displayed altered lung tissue cytokine responses 2 and 4 days postinfection compared to those of untreated animals, suggesting that one possible mechanism of action for RTD-1 is immunomodulatory.