| 25194747 |
Discovery of a new subclass of α-conotoxins in the venom of Conus australis |
10.1016/j.toxicon.2014.08.074. |
Toxicon |
Discovery of a new subclass of α-conotoxins in the venom of Conus australis
Abstract
- Cone snails (Conus sp.) are poisonous animals that can be found in all oceans where they developed a venomous strategy to prey or to defend. The venom of these species contains an undeniable source of unique and potent pharmacologically active compounds. Their peptide compounds, called conotoxins, are not only interesting for the development of new pharmaceutical ligands, but they are also useful for studying their broad spectrum of targets. One conotoxin family in particular, the α-conotoxins, acts on nicotinic acetylcholine receptors (nAChRs) which dysfunctions play important roles in pathologies such as epilepsy, myasthenic syndromes, schizophrenia, Parkinson's disease and Alzheimer's disease. Here we define a new subclass of the α-conotoxin family. We purified the venom of a yet unexplored cone snail species, i.e. Conus australis, and we isolated a 16-amino acid peptide named α-conotoxin AusIA. The peptide has the typical α-conotoxin CC-Xm-C-Xn-C framework, but both loops (m/n) contain 5 amino acids, which has never been described before. Using conventional electrophysiology we investigated the response of synthetically made globular (I-III, II-IV) and ribbon (I-IV, II-III) AusIA to different nicotinic acetylcholine receptors. The α7 nAChR was the only receptor found to be blocked with a similar potency by both peptide-configurations. This suggests that both α5/5 conotoxin isomers might be present in the venom gland of C. australis. NMR spectroscopy showed that no secondary structures define the peptides' three-dimensional topology. Moreover, the ribbon configuration, which is generally considered to be non-native, is more stable than the globular isomer. Accordingly, our findings show relevancy concerning the α-conotoxin classification which might be helpful in the design of novel therapeutic compounds.
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| 25200101 |
Jatrophidin I, a cyclic peptide from Brazilian Jatropha curcas L.: isolation, characterization, conformational studies and biological activity |
10.1016/j.phytochem.2014.08.006. |
Phytochemistry |
Jatrophidin I, a cyclic peptide from Brazilian Jatropha curcas L.: isolation, characterization, conformational studies and biological activity
Abstract
- A cyclic peptide, jatrophidin I, was isolated from the latex of Jatropha curcas L. Its structure was elucidated by extensive 2D NMR spectroscopic analysis, with additional conformational studies performed using Molecular Dynamics/Simulated Annealing (MD/SA). Jatrophidin I had moderate protease inhibition activity when compared with pepstatin A; however, the peptide was inactive in antimalarial, cytotoxic and antioxidant assays.
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| 25212039 |
[A cyclotide against influenza A H1N1 virus from Viola yedoensis] |
None |
Yao Xue Xue Bao |
[A cyclotide against influenza A H1N1 virus from Viola yedoensis]
Abstract
- Three cyclotides were isolated from the whole plant of Viola yedoensis in this study. The two, vary peptide E and cycloviolacin Y5, were previously reported, and a novel cycloviolacin VY1 was characterized according to the interpretation of MS/MS fragmentation of peptides which were produced from the reduced and alkylated parent peptide with the digestion of Endo Lys-C, trypsin and chymotrypsin, separately. The stability of remarkable resistance to proteolytic degradation by trypsin and chymotrypsin, and that of thermal denaturation was confirmed again. Besides, the IC50 value of cycloviolacin VY1 against influenza A H1N1 virus was (2.27 +/- 0.20) microg x mL(-1). It is the first cyclotide reported with anti-influenza A H1N1 virus activity in vitro assay.
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| 25218447 |
Uncovering global SUMOylation signaling networks in a site-specific manner |
10.1038/nsmb.2890. |
Nat Struct Mol Biol |
Uncovering global SUMOylation signaling networks in a site-specific manner
Abstract
- SUMOylation is a reversible post-translational modification essential for genome stability. Using high-resolution MS, we have studied global SUMOylation in human cells in a site-specific manner, identifying a total of >4,300 SUMOylation sites in >1,600 proteins. To our knowledge, this is the first time that >1,000 SUMOylation sites have been identified under standard growth conditions. We quantitatively studied SUMOylation dynamics in response to SUMO protease inhibition, proteasome inhibition and heat shock. Many SUMOylated lysines have previously been reported to be ubiquitinated, acetylated or methylated, thus indicating cross-talk between SUMO and other post-translational modifications. We identified 70 phosphorylation and four acetylation events in proximity to SUMOylation sites, and we provide evidence for acetylation-dependent SUMOylation of endogenous histone H3. SUMOylation regulates target proteins involved in all nuclear processes including transcription, DNA repair, chromatin remodeling, precursor-mRNA splicing and ribosome assembly.
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| 25229313 |
Wollamides: antimycobacterial cyclic hexapeptides from an Australian soil Streptomyces |
10.1021/ol502472c. |
Org Lett |
Wollamides: antimycobacterial cyclic hexapeptides from an Australian soil Streptomyces
Abstract
- A soil Streptomyces nov. sp. (MST-115088) isolated from semiarid terrain near Wollogorang Station, Queensland, returned two known and two new examples of a rare class of cyclic hexapeptide, desotamides A and B (1 and 2) and E and F (3 and 4), respectively, together with two new d-Orn homologues, wollamides A and B (5 and 6). Structures were assigned by detailed spectroscopic and C3 Marfey's analysis. The desotamides/wollamides exhibit growth inhibitory activity against Gram-positive bacteria (IC50 0.6-7 μM) and are noncytotoxic to mammalian cells (IC50 >30 μM). The wollamides exhibit antimycobacterial activity (IC50 2.8 and 3.1 μM), including reduction in the intracellular mycobacterial survival in murine bone marrow-derived macrophages.
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| 25255805 |
Global profiling of co- and post-translationally N-myristoylated proteomes in human cells. |
10.1038/ncomms5919 |
Nat. Commun. |
Global profiling of co- and post-translationally N-myristoylated proteomes in human cells.
Abstract
- Protein N-myristoylation is a ubiquitous co- and post-translational modification that has been implicated in the development and progression of a range of human diseases. Here, we report the global N-myristoylated proteome in human cells determined using quantitative chemical proteomics combined with potent and specific human N-myristoyltransferase (NMT) inhibition. Global quantification of N-myristoylation during normal growth or apoptosis allowed the identification of >100 N-myristoylated proteins, >95% of which are identified for the first time at endogenous levels. Furthermore, quantitative dose response for inhibition of N-myristoylation is determined for >70 substrates simultaneously across the proteome. Small-molecule inhibition through a conserved substrate-binding pocket is also demonstrated by solving the crystal structures of inhibitor-bound NMT1 and NMT2. The presented data substantially expand the known repertoire of co- and post-translational N-myristoylation in addition to validating tools for the pharmacological inhibition of NMT in living cells.
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| 25265024 |
Autumnalamide, a prenylated cyclic peptide from the cyanobacterium Phormidium autumnale, acts on SH-SY5Y cells at the mitochondrial level |
10.1021/np500374a. |
J Nat Prod |
Autumnalamide, a prenylated cyclic peptide from the cyanobacterium Phormidium autumnale, acts on SH-SY5Y cells at the mitochondrial level
Abstract
- Filamentous cyanobacteria of the genus Phormidium have been rarely studied for their chemical diversity. For the first time, the cultivable Phormidium autumnale was shown to produce a prenylated cyclic peptide named autumnalamide (1). The structure of this peptide was fully determined after a deep exploration of the spectroscopic data, including NMR and HRMS. Interestingly, a prenyl moiety was located on the guanidine end of the arginine amino acid. The absolute configurations of most amino acids were assessed using enantioselective GC/MS analysis, with (13)C NMR modeling being used for the determination of d-arginine and d-proline. The effects of 1 on sodium and calcium fluxes were studied in SH-SY5Y and hNav 1.6 HEK cells. When the Ca(2+) influx was stimulated by thapsigargin, strong inhibition was observed in the presence of 1. As a consequence, this compound may act by disrupting the normal calcium uptake of this organelle, inducing the opening of the mitochondrial permeability transition pore, which results in the indirect blockade of store-operated channels.
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| 25270390 |
Pneumocandin biosynthesis: involvement of a trans-selective proline hydroxylase |
10.1002/cbic.201402175. |
Chembiochem |
Pneumocandin biosynthesis: involvement of a trans-selective proline hydroxylase
Abstract
- Echinocandins are cyclic nonribosomal hexapeptides based mostly on nonproteinogenic amino acids and displaying strong antifungal activity. Despite previous studies on their biosynthesis by fungi, the origin of three amino acids, trans-4- and trans-3-hydroxyproline, as well as trans-3-hydroxy-4-methylproline, is still unknown. Here we describe the identification, overexpression, and characterization of GloF, the first eukaryotic α-ketoglutarate/Fe(II) -dependent proline hydroxylase from the pneumocandin biosynthesis cluster of the fungus Glarea lozoyensis ATCC 74030. In in vitro transformations with L-proline, GloF generates trans-4- and trans-3-hydroxyproline simultaneously in a ratio of 8:1; the latter reaction was previously unknown for proline hydroxylase catalysis. trans-4-Methyl-L-proline is converted into the corresponding trans-3-hydroxyproline. All three hydroxyprolines required for the biosynthesis of the echinocandins pneumocandins A0 and B0 in G. lozoyensis are thus provided by GloF. Sequence analyses revealed that GloF is not related to bacterial proline hydroxylases, and of the putative proteins with high sequence similarity in the databases has been characterized so far.
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| 25294122 |
Fibrinolysis and the control of blood coagulation |
10.1016/j.blre.2014.09.003. |
Blood Rev |
Fibrinolysis and the control of blood coagulation
Abstract
- Fibrin plays an essential role in hemostasis as both the primary product of the coagulation cascade and the ultimate substrate for fibrinolysis. Fibrinolysis efficiency is greatly influenced by clot structure, fibrinogen isoforms and polymorphisms, the rate of thrombin generation, the reactivity of thrombus-associated cells such as platelets, and the overall biochemical environment. Regulation of the fibrinolytic system, like that of the coagulation cascade, is accomplished by a wide array of cofactors, receptors, and inhibitors. Fibrinolytic activity can be generated either on the surface of a fibrin-containing thrombus, or on cells that express profibrinolytic receptors. In a widening spectrum of clinical disorders, acquired and congenital defects in fibrinolysis contribute to disease morbidity, and new assays of global fibrinolysis now have potential predictive value in multiple clinical settings. Here, we summarize the basic elements of the fibrinolytic system, points of interaction with the coagulation pathway, and some recent clinical advances.
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| 25307803 |
Lanreotide autogel in acromegaly - a decade on |
10.1517/14656566.2014.970173. |
Expert Opin Pharmacother |
Lanreotide autogel in acromegaly - a decade on
Abstract
- The novel formulation of lanreotide, lanreotide (LAN) autogel (ATG), has been available in Europe since 2001 and USA from 2006 for the treatment of acromegaly. It is one of only two clinically available somatostatin analogs available for use in acromegaly. Data relating to the use of ATG in acromegaly, specifically relating to comparison to octreotide (OCT) LAR and patient acceptability and preference, have been slow to accumulate.
We performed a comprehensive review of the original literature relating to development, pharmacokinetics, acceptability and clinical efficacy of ATG.
LAN ATG is a novel formulation of LAN consequent on self-assembly of nanotubules in water. Diffusion between molecules within the nanotubules and surrounding tissue fluid in vivo leads to pseudo first-order pharmacokinetics. Efficacy is equivalent to the alternate long-acting somatostatin analog, OCT LAR, normalizing growth hormone and IGF-I levels in around 60 and 50% respectively. Control of tumor growth is observed in over 95% of patients, with 64% seeing a clinically significant reduction in tumor size. ATG is provided in a prefilled syringe for deep subcutaneous injection, allowing self-injection, and may be administered up to 8 weeks greatly improving convenience for the patient. The data strongly support consideration of ATG as the medical therapy of choice for patients with acromegaly.
|
| 25310285 |
RNA-seq analysis of the effect of kanamycin and the ABC transporter AtWBC19 on Arabidopsis thaliana seedlings reveals changes in metal content |
10.1371/journal.pone.0109310. |
PLoS One |
RNA-seq analysis of the effect of kanamycin and the ABC transporter AtWBC19 on Arabidopsis thaliana seedlings reveals changes in metal content
Abstract
- Plants are exposed to antibiotics produced by soil microorganisms, but little is known about their responses at the transcriptional level. Likewise, few endogenous mechanisms of antibiotic resistance have been reported. The Arabidopsis thaliana ATP Binding Cassette (ABC) transporter AtWBC19 (ABCG19) is known to confer kanamycin resistance, but the exact mechanism of resistance is not well understood. Here we examined the transcriptomes of control seedlings and wbc19 mutant seedlings using RNA-seq analysis. Exposure to kanamycin indicated changes in the organization of the photosynthetic apparatus, metabolic fluxes and metal uptake. Elemental analysis showed a 60% and 80% reduction of iron uptake in control and wbc19 mutant seedlings respectively, upon exposure to kanamycin. The drop in iron content was accompanied by the upregulation of the gene encoding for FERRIC REDUCTION OXIDASE 6 (FRO6) in mutant seedlings but not by the differential expression of other transport genes known to be induced by iron deficiency. In addition, wbc19 mutants displayed a distinct expression profile in the absence of kanamycin. Most notably the expression of several zinc ion binding proteins, including ZINC TRANSPORTER 1 PRECURSOR (ZIP1) was increased, suggesting abnormal zinc uptake. Elemental analysis confirmed a 50% decrease of zinc content in wbc19 mutants. Thus, the antibiotic resistance gene WBC19 appears to also have a role in zinc uptake.
|
| 25311788 |
EGFR phosphorylates and inhibits lung tumor suppressor GPRC5A in lung cancer |
10.1186/1476-4598-13-233. |
Mol Cancer |
EGFR phosphorylates and inhibits lung tumor suppressor GPRC5A in lung cancer
Abstract
- Background:
GPRC5A is a retinoic acid inducible gene that is preferentially expressed in lung tissue. Gprc5a- knockout mice develop spontaneous lung cancer, indicating Gprc5a is a lung tumor suppressor gene. GPRC5A expression is frequently suppressed in majority of non-small cell lung cancers (NSCLCs), however, elevated GPRC5A is still observed in a small portion of NSCLC cell lines and tumors, suggesting that the tumor suppressive function of GPRC5A is inhibited in these tumors by an unknown mechanism.
Methods:
In this study, we examined EGF receptor (EGFR)-mediated interaction and tyrosine phosphorylation of GPRC5A by immunoprecipitation (IP)-Westernblot. Tyrosine phosphorylation of GPRC5A by EGFR was systematically identified by site-directed mutagenesis. Cell proliferation, migration, and anchorage-independent growth of NSCLC cell lines stably transfected with wild-type GPRC5A and mutants defective in tyrosine phosphorylation were assayed. Immunohistochemical (IHC) staining analysis with specific antibodies was performed to measure the total and phosphorylated GPRC5A in both normal lung and lung tumor tissues.
Result:
We found that EGFR interacted with GPRC5A and phosphorylated it in two conserved double-tyrosine motifs, Y317/Y320 and Y347/ Y350, at the C-terminal tail of GPRC5A. EGF induced phosphorylation of GPRC5A, which disrupted GPRC5A-mediated suppression on anchorage-independent growth of NSCLC cells. On contrary, GPRC5A-4 F, in which the four tyrosine residues have been replaced with phenylalanine, was resistant to EGF-induced phosphorylation and maintained tumor suppressive activities. Importantly, IHC analysis with anti-Y317/Y320-P sites showed that GPRC5A was non-phosphorylated in normal lung tissue whereas it was highly tyrosine-phosphorylated in NSCLC tissues.
Conclusion:
GPRC5A can be inactivated by receptor tyrosine kinase via tyrosine phosphorylation. Thus, targeting EGFR can restore the tumor suppressive functions of GPRC5A in lung cancer.
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| 25369268 |
Meningiomas: a comparative study of 68Ga-DOTATOC, 68Ga-DOTANOC and 68Ga-DOTATATE for molecular imaging in mice |
10.1371/journal.pone.0111624. |
PLoS One |
Meningiomas: a comparative study of 68Ga-DOTATOC, 68Ga-DOTANOC and 68Ga-DOTATATE for molecular imaging in mice
Abstract
- The goal of this study was to compare the tumor uptake kinetics and diagnostic value of three (68)Ga-DOTA-labeled somatostatin analogues ((68)Ga-DOTATOC, (68)Ga-DOTANOC, and (68)Ga-DOTATATE) using PET/CT in a murine model with subcutaneous meningioma xenografts.
The experiment was performed with 16 male NUDE NU/NU mice bearing xenografts of a human meningioma cell line (CH-157MN). (68)Ga-DOTATOC, (68)Ga-DOTANOC, and (68)Ga-DOTATATE were produced in a FASTLab automated platform. Imaging was performed on an Argus small-animal PET/CT scanner. The SUVmax of the liver and muscle, and the tumor-to-liver (T/L) and tumor-to-muscle (T/M) SUV ratios were computed. Kinetic analysis was performed using Logan graphical analysis for a two-tissue reversible compartmental model, and the volume of distribution (Vt) was determined.
Hepatic SUVmax and Vt were significantly higher with (68)Ga-DOTANOC than with (68)Ga-DOTATOC and (68)Ga-DOTATATE. No significant differences between tracers were found for SUVmax in tumor or muscle. No differences were found in the T/L SUV ratio between (68)Ga-DOTATATE and (68)Ga-DOTATOC, both of which had a higher fraction than (68)Ga-DOTANOC. The T/M SUV ratio was significantly higher with (68)Ga-DOTATATE than with (68)Ga-DOTATOC and (68)Ga-DOTANOC. The Vt for tumor was higher with (68)Ga-DOTATATE than with (68)Ga-DOTANOC and relatively similar to that of (68)Ga-DOTATOC.
This study demonstrates, for the first time, the ability of the three radiolabeled somatostatin analogues tested to image a human meningioma cell line. Although Vt was relatively similar with (68)Ga-DOTATATE and (68)Ga-DOTATOC, uptake was higher with (68)Ga-DOTATATE in the tumor than with (68)Ga-DOTANOC and (68)Ga-DOTATOC, suggesting a higher diagnostic value of (68)Ga-DOTATATE for detecting meningiomas.
|
| 25371290 |
Exploring the diversity and metabolic potential of actinomycetes from temperate marine sediments from Newfoundland, Canada |
10.1007/s10295-014-1529-x. |
J Ind Microbiol Biotechnol |
Exploring the diversity and metabolic potential of actinomycetes from temperate marine sediments from Newfoundland, Canada
Abstract
- Marine sediments from Newfoundland, Canada were explored for biotechnologically promising Actinobacteria using culture-independent and culture-dependent approaches. Culture-independent pyrosequencing analyses uncovered significant actinobacterial diversity (H'-2.45 to 3.76), although the taxonomic diversity of biotechnologically important actinomycetes could not be fully elucidated due to limited sampling depth. Assessment of culturable actinomycete diversity resulted in the isolation of 360 actinomycetes representing 59 operational taxonomic units, the majority of which (94 %) were Streptomyces. The biotechnological potential of actinomycetes from NL sediments was assessed by bioactivity and metabolomics-based screening of 32 representative isolates. Bioactivity was exhibited by 41 % of isolates, while 11 % exhibited unique chemical signatures in metabolomics screening. Chemical analysis of two isolates resulted in the isolation of the cytotoxic metabolite 1-isopentadecanoyl-3β-D-glucopyranosyl-X-glycerol from Actinoalloteichus sp. 2L868 and sungsanpin from Streptomyces sp. 8LB7. These results demonstrate the potential for the discovery of novel bioactive metabolites from actinomycetes isolated from Atlantic Canadian marine sediments.
|
| 25376175 |
The evolution of Momordica cyclic peptides |
10.1093/molbev/msu307. |
Mol Biol Evol |
The evolution of Momordica cyclic peptides
Abstract
- Cyclic proteins have evolved for millions of years across all kingdoms of life to confer structural stability over their acyclic counterparts while maintaining intrinsic functional properties. Here, we show that cyclic miniproteins (or peptides) from Momordica (Cucurbitaceae) seeds evolved in species that diverged from an African ancestor around 19 Ma. The ability to achieve head-to-tail cyclization of Momordica cyclic peptides appears to have been acquired through a series of mutations in their acyclic precursor coding sequences following recent and independent gene expansion event(s). Evolutionary analysis of Momordica cyclic peptides reveals sites that are under selection, highlighting residues that are presumably constrained for maintaining their function as potent trypsin inhibitors. Molecular dynamics of Momordica cyclic peptides in complex with trypsin reveals site-specific residues involved in target binding. In a broader context, this study provides a basis for selecting Momordica species to further investigate the biosynthesis of the cyclic peptides and for constructing libraries that may be screened against evolutionarily related serine proteases implicated in human diseases.
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