| 22765903 |
Synthesis of a Microcystis aeruginosa predicted metabolite with antimalarial activity |
10.1016/j.bmcl.2012.06.028. |
Bioorg Med Chem Lett |
Synthesis of a Microcystis aeruginosa predicted metabolite with antimalarial activity
Abstract
- The synthesis of a Microcystis aeruginosa predicted metabolite analog of aerucyclamide B was performed. This hexacyclopeptide was obtained from three heterocyclic building blocks by a convergent macrocycle-assembly methodology. The compound exhibited good in vitro antiplasmodial activity (IC(50): 0.18 μM, K1, cholorquine resistant strain).
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| 22781954 |
Diversity and evolution of conotoxins in Conus virgo, Conus eburneus, Conus imperialis and Conus marmoreus from the South China Sea |
10.1016/j.toxicon.2012.06.011. |
Toxicon |
Diversity and evolution of conotoxins in Conus virgo, Conus eburneus, Conus imperialis and Conus marmoreus from the South China Sea
Abstract
- The venom peptides of cone snails are encoded by a large gene family, and can selectively bind to voltage-gated ion channels (Na⁺, K⁺ and Ca²⁺ channels) and to membrane receptors (nAChR, 5-HT3R, NMDAR). To identify novel conotoxin genes and analyze the evolution of typical conotoxin superfamily genes from different Conus species, we have constructed cDNA libraries derived from the venom ducts of Conus virgo, Conus eburneus, Conus imperialis and Conus marmoreus, which were collected from the South China Sea. 1312 transcripts from four Conus venom duct cDNA libraries were analyzed and 38.7-49.6% of the transcripts encoded conotoxin sequences. In addition to known conotoxins, 34 novel conotoxins have been identified and can be classified into eleven superfamilies, some of which showed unique patterns of cysteines or different signal peptide sequences. The evolutionary trees of T- and A-superfamily conotoxins were analyzed. Likelihood approaches revealed that T-superfamily conotoxins from the four Conus species undergo positive selection, mostly located in the mature toxin region. These findings contribute to a better understanding of the diversity and evolution of conotoxins from the South China Sea, and some novel conotoxins are valuable for further functional investigations.
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| 22790026 |
[Overview of structural study on conformations and intermolecular interactions of biomolecules] |
10.1248/yakushi.132.785. |
Yakugaku Zasshi |
[Overview of structural study on conformations and intermolecular interactions of biomolecules]
Abstract
- Information on the conformational feature and specific intermolecular interaction of biomolecules is important to understand the biological function and to develop device for treating disorder caused by the abnormal function. Thus the 3D structures of the biologically active molecules and the specific interactions with their target molecules at the atomic level have been investigated by various physicochemical approaches. Herein, the following five subjects are reviewed: (1) function-linked conformations of biomolecules including natural annular products, opioid peptides and neuropeptides; (2) π-π stacking interactions of tryptophan derivatives with coenzymes and nucleic acid bases; (3) mRNA cap recognition of eukaryotic initiation factor 4E and its regulation by 4E-binding protein; (4) conformational feature of histamine H2 receptor antagonists and design of cathepsin B inhibitors; (5) self-aggregation mechanism of tau protein and its inhibition.
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| 22802270 |
Efficient binding of 4/7 α-conotoxins to nicotinic α4β2 receptors is prevented by Arg185 and Pro195 in the α4 subunit |
10.1124/mol.112.078683. |
Mol Pharmacol |
Efficient binding of 4/7 α-conotoxins to nicotinic α4β2 receptors is prevented by Arg185 and Pro195 in the α4 subunit
Abstract
- α-Conotoxins are subtype-selective nicotinic acetylcholine receptor (nAChR) antagonists. Although potent α3β2 nAChR-selective α-conotoxins have been identified, currently characterized α-conotoxins show no or only weak affinity for α4β2 nAChRs, which are, besides α7 receptors, the most abundant nAChRs in the mammalian brain. To identify the determinants responsible for this difference, we substituted selected amino acid residues in the ligand-binding domain of the α4 subunit by the corresponding residues in the α3 subunit. Two-electrode voltage clamp analysis of these mutants revealed increased affinity of α-conotoxins MII, TxIA, and [A10L]TxIA at the α4(R185I)β2 receptor. Conversely, α-conotoxin potency was reduced at the reverse α3(I186R)β2 mutant. Replacement of α4Arg185 by alanine, glutamate, and lysine demonstrated that a positive charge in this position prevents α-conotoxin binding. Combination of the R185I mutation with a P195Q mutation outside the binding site but in loop C completely transferred high α-conotoxin potency to the α4β2 receptor. Molecular dynamics simulations of homology models with docked α-conotoxin indicate that these residues control access to the α-conotoxin binding site.
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| 22814378 |
N-terminal acetylome analyses and functional insights of the N-terminal acetyltransferase NatB. |
10.1073/pnas.1210303109 |
Proc. Natl. Acad. Sci. U.S.A. |
N-terminal acetylome analyses and functional insights of the N-terminal acetyltransferase NatB.
Abstract
- Protein N-terminal acetylation (Nt-acetylation) is an important mediator of protein function, stability, sorting, and localization. Although the responsible enzymes are thought to be fairly well characterized, the lack of identified in vivo substrates, the occurrence of Nt-acetylation substrates displaying yet uncharacterized N-terminal acetyltransferase (NAT) specificities, and emerging evidence of posttranslational Nt-acetylation, necessitate the use of genetic models and quantitative proteomics. NatB, which targets Met-Glu-, Met-Asp-, and Met-Asn-starting protein N termini, is presumed to Nt-acetylate 15% of all yeast and 18% of all human proteins. We here report on the evolutionary traits of NatB from yeast to human and demonstrate that ectopically expressed hNatB in a yNatB-Δ yeast strain partially complements the natB-Δ phenotypes and partially restores the yNatB Nt-acetylome. Overall, combining quantitative N-terminomics with yeast studies and knockdown of hNatB in human cell lines, led to the unambiguous identification of 180 human and 110 yeast NatB substrates. Interestingly, these substrates included Met-Gln- N-termini, which are thus now classified as in vivo NatB substrates. We also demonstrate the requirement of hNatB activity for maintaining the structure and function of actomyosin fibers and for proper cellular migration. In addition, expression of tropomyosin-1 restored the altered focal adhesions and cellular migration defects observed in hNatB-depleted HeLa cells, indicative for the conserved link between NatB, tropomyosin, and actin cable function from yeast to human.
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| 22822203 |
Cyclic peptides arising by evolutionary parallelism via asparaginyl-endopeptidase-mediated biosynthesis |
10.1105/tpc.112.099085. |
Plant Cell |
Cyclic peptides arising by evolutionary parallelism via asparaginyl-endopeptidase-mediated biosynthesis
Abstract
- The cyclic miniprotein Momordica cochinchinensis Trypsin Inhibitor II (MCoTI-II) (34 amino acids) is a potent trypsin inhibitor (TI) and a favored scaffold for drug design. We have cloned the corresponding genes and determined that each precursor protein contains a tandem series of cyclic TIs terminating with the more commonly known, and potentially ancestral, acyclic TI. Expression of the precursor protein in Arabidopsis thaliana showed that production of the cyclic TIs, but not the terminal acyclic TI, depends on asparaginyl endopeptidase (AEP) for maturation. The nature of their repetitive sequences and the almost identical structures of emerging TIs suggest these cyclic peptides evolved by internal gene amplification associated with recruitment of AEP for processing between domain repeats. This is the third example of similar AEP-mediated processing of a class of cyclic peptides from unrelated precursor proteins in phylogenetically distant plant families. This suggests that production of cyclic peptides in angiosperms has evolved in parallel using AEP as a constraining evolutionary channel. We believe this is evolutionary evidence that, in addition to its known roles in proteolysis, AEP is especially suited to performing protein cyclization.
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| 22824869 |
Total synthesis and stereochemical revision of lagunamide A |
10.1039/c2cc34187e. |
Chem Commun (Camb) |
Total synthesis and stereochemical revision of lagunamide A
Abstract
- A revised configurational assignment for the marine metabolite lagunamide A is proposed and validated by total synthesis.
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| 22825834 |
Expression, renaturation and biological activity of recombinant conotoxin GeXIVAWT |
10.1007/s00253-012-4287-6. |
Appl Microbiol Biotechnol |
Expression, renaturation and biological activity of recombinant conotoxin GeXIVAWT
Abstract
- Conotoxins are a diverse array of small peptides mostly with multiple disulfide bridges. These peptides become an increasing significant source of neuro-pharmacological probes and drugs as a result of the high selectivity for ion channels and receptors. Conotoxin GeXIVAWT (CTX-GeXIVAWT) is a 28-amino acid peptide containing five cysteines isolated from the venom of Conus generalis. Here, we present a simple and fast strategy of producing disulfide-rich conotoxins via recombinant expression. The codes of novel conotoxin gene GeXIVAWT were optimized and generated two pairs of primers by chemical synthesis for construction of expression vector. Recombinant expression vector pET22b(+)-GeXIVAWT fused with pelB leader and His-tag was successfully expressed as an insoluble body in Escherichia coli BL21(DE3) cells. Recombinant conotoxin GeXIVAWT (rCTX-GeXIVAWT) was obtained by dissolving the insoluble bodies and purifying with a Ni-NTA affinity column, which was further purified using reverse-phase high-performance liquid chromatography and identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. The rCTX-GeXIVAWT renatured in vitro could inhibited the growth of Sf9 cell with biological activity assay. This expression system may prove valuable for future structure-function studies of conotoxins.
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| 22828809 |
Antimicrobial peptide diversity in the skin of the torrent frog, Amolops jingdongensis |
10.1007/s00726-012-1358-z. |
Amino Acids |
Antimicrobial peptide diversity in the skin of the torrent frog, Amolops jingdongensis
Abstract
- Antimicrobial peptide diversity has been found in some amphibians. The diversity of antimicrobial peptides may have resulted from the diversity of microorganisms encountered by amphibians. Peptidomics and genomics analyses were used to study antimicrobial peptide diversity in the skin secretions of the torrent frog, Amolops jingdongensis. Thirty-one antimicrobial peptides belonging to nine groups were identified in the skin secretions of this frog. Among them, there are two novel antimicrobial groups (jingdongin-1 and -2) with unique structural motifs. The other seven groups belong to known antimicrobial peptide families, namely brevinin-1, brevinin-2, odorranain-F, esculentin-2, temporin, amolopin-3, and ranacyclin. Combined with previous reports, more than 13 antimicrobial peptide groups have been identified from the genus Amolops. Most of these antimicrobial peptide groups are also found in amphibians belonging to the genus Rana or Odorrana which suggests a possible evolutionary connection among Amolops, Rana, and Odorrana. Two novel antimicrobial groups (jingdongin-1 and -2) were synthesized and their antimicrobial activities were assayed. Some of them showed strong antimicrobial abilities against microorganisms including Gram-negative and -positive bacteria, and fungi. The extreme diversity of antimicrobial peptides in the Amolops amphibians was demonstrated. In addition, several novel peptide templates were provided for antimicrobial agent design.
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| 22846083 |
Host-selective toxins produced by the plant pathogenic fungus Alternaria alternata |
10.1111/j.1574-6976.2012.00350.x. |
FEMS Microbiol Rev |
Host-selective toxins produced by the plant pathogenic fungus Alternaria alternata
Abstract
- Host-selective toxins (HSTs) produced by fungal plant pathogens are generally low-molecular-weight secondary metabolites with a diverse range of structures that function as effectors controlling pathogenicity or virulence in certain plant-pathogen interactions. There are now seven known diseases caused by Alternaria alternata in which HSTs are responsible for fungal pathogenesis. The pathogens have been defined as pathotypes of A. alternata because of morphological similarity but pathological differences. Chemical structures of HSTs from six pathotypes have been determined. The role of A. alternata HSTs in pathogenesis has been studied extensively, and discovery of the release of HSTs from germinating conidia prior to penetration aids in understanding the early participation of HSTs to induce susceptibility of host cells by suppressing their defence reactions. Many attempts have been made to find the target sites of A. alternata HSTs, and four cellular components, plasma membrane, mitochondrion, chloroplast and a metabolically important enzyme, have been identified as the primary sites of each HST action, leading to elucidation of the molecular mechanisms of HST sensitivity in host plants. Studies of the molecular genetics of HST production have identified supernumerary chromosomes encoding HST gene clusters and have provided new insights into the evolution of A. alternata pathotypes.
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| 22847390 |
Lipopeptides from the banyan endophyte, Bacillus subtilis K1: mass spectrometric characterization of a library of fengycins |
10.1007/s13361-012-0437-4. |
J Am Soc Mass Spectrom |
Lipopeptides from the banyan endophyte, Bacillus subtilis K1: mass spectrometric characterization of a library of fengycins
Abstract
- Mass spectrometric analysis of a banyan endophyte, Bacillus subtilis K1, extract showing broad spectrum antifungal activity revealed a complex mixture of lipopeptides, iturins, surfactins, and fengycins. Fractionation by reversed-phase high performance liquid chromatography (HPLC) facilitated a detailed analysis of fengycin microheterogeneity. Matrix assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometric studies permitted the identification of several new fengycin variants. Four major sites of heterogeneity are identified: (1) N-terminus β-hydroxy fatty acid moiety, where chain length variation and the presence of unsaturation occur, (2) position 6 (Ala/Val/Ile/Leu), (3) position 10 (Val/Ile) within the macrocyclic ring, and (4) Gln to Glu replacement at position 8, resulting in fengycin variants that differ in mass by 1 Da. Diagnostic fragment ions provide a quick method for localizing the sites of variation in the macrocycle or the linear segment. Subsequent establishment of the sequences is achieved by MS/MS analysis of linear fengycin species produced by hydrolysis of the macrocyclic lactone. Unsaturation in the fatty acid chain and the presence of linear precursors in the B. subtilis K1 extract are also established by mass spectrometry. The anomalous distribution of intensities within isotopic multiplets is a diagnostic for Gln/Glu replacements. High resolution mass spectrometry facilitates the identification of fengycin species differing by 1 Da by localizing the variable position (Gln(8)/Glu(8)) in the fengycin variants.
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| 22851252 |
Role of the backbone conformation at position 7 in the structure and activity of marinostatin, an ester-linked serine protease inhibitor |
10.1002/cbic.201200315. |
Chembiochem |
Role of the backbone conformation at position 7 in the structure and activity of marinostatin, an ester-linked serine protease inhibitor
Abstract
- Rational design of inhibitors: The cis-amide backbone at position 7 in the serine protease inhibitor marinostatin was replaced with an E or Z olefin. The E olefin analogue was not active, but the Z analogue was. The cis conformation might play a critical role in organizing a canonical structure for binding to proteases.
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| 22853450 |
A topical aqueous calcineurin inhibitor for the treatment of naturally occurring keratoconjunctivitis sicca in dogs |
10.1111/j.1463-5224.2012.01056.x. |
Vet Ophthalmol |
A topical aqueous calcineurin inhibitor for the treatment of naturally occurring keratoconjunctivitis sicca in dogs
Abstract
- The purpose of this study was to evaluate the efficacy of an aqueous calcineurin inhibitor, SCY-641, in the treatment of naturally occurring canine immune-mediated keratoconjunctivitis sicca (KCS).
A randomized, double-masked, placebo-controlled clinical study of 56-day duration was performed in dogs with naturally occurring immune-mediated KCS assigned to treatment with either topical twice-daily aqueous calcineurin inhibitor solution (SCY-641) or artificial tears (placebo) by the study administrator. Clinical examination and Schirmer tear tests (STT) were performed prior to therapy and at days 7, 14, 28, and 56 after initiation of treatment.
Twenty dogs were enrolled in the study with ten receiving placebo and 10 receiving SCY-641 in one or both eyes. No adverse effects were noted with any treatment. There were no significant differences in mean STT values in dogs in group either at day 0 (prior to therapy) or after 7 days of treatment. At 14, 28, and 56 days after initiation of treatment, mean STT and increase in STT over baseline in dogs treated with SCY-641 were significantly higher than in dogs treated with placebo (P < 0.04).
SCY-641 was well tolerated by dogs with naturally occurring KCS, and by 14 days after initiating therapy, dogs treated with SCY-641 had significantly higher STT than placebo-treated dogs. These preliminary results indicate that topical SCY-641, in a stable clear aqueous solution, is efficacious in a spontaneous model of KCS and warrants further evaluation as a treatment of immune-mediated KCS.
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| 22858902 |
Total synthesis of the proposed structure of cyclic hexadepsipeptide veraguamide A |
10.1039/c2ob26002f. |
Org Biomol Chem |
Total synthesis of the proposed structure of cyclic hexadepsipeptide veraguamide A
Abstract
- We have developed a practical method to assemble the proposed structure of natural product veraguamide A (1) by first preparing the three key fragments followed by optimization of the macrocyclization site. Although the synthetic product gave similar optical rotation to that reported for natural product, significant differences in the (1)H and (13)C NMR spectra were observed, especially the proton and carbon signals in the two N-MeVal moieties.
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| 22859244 |
The use of cyclosporine in dermatology |
None |
J Drugs Dermatol |
The use of cyclosporine in dermatology
Abstract
- Cyclosporine is an immunosuppressive drug that acts selectively on T-cells by inhibiting calcineurin phosphorylase. It has been used in dermatology since its approval for US Food and Drug Administration in 1997 for the use in psoriasis. While indicated only for the treatment of moderate to severe psoriasis, cyclosporine has also been used as an off-label drug for the treatment of various inflammatory skin conditions, including atopic dermatitis, blistering disorders, and connective tissue diseases. In this article, we review the use of cyclosporine in dermatology.
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