| 17685615 |
Crystal structure of a biosynthetic sulfo-hirudin complexed to thrombin |
10.1021/ja0735002. |
J Am Chem Soc |
Crystal structure of a biosynthetic sulfo-hirudin complexed to thrombin
Abstract
|
| 17688900 |
Cytolytic peptides belonging to the brevinin-1 and brevinin-2 families isolated from the skin of the Japanese brown frog, Rana dybowskii |
10.1016/j.toxicon.2007.06.023. |
Toxicon |
Cytolytic peptides belonging to the brevinin-1 and brevinin-2 families isolated from the skin of the Japanese brown frog, Rana dybowskii
Abstract
- Peptidomic analysis of an extract of the skins of specimens of Dybowski's brown frog Rana dybowskii Gunther, 1876, collected on Tsushima Island, Japan led to the identification of 10 peptides with differential antibacterial and hemolytic activities. The primary structures of these peptides identified them as belonging to the brevinin-1 (5 peptides) and brevinin-2 (5 peptides) families of antimicrobial peptides. A peptide (FIGPIISALASLFG.NH(2)) with structural similarity to members of the temporin family was also isolated but this component lacked cytolytic activity. Phylogenetic relationships among the Japanese brown frogs (R. dybowskii, R. japonica, R. okinavana, R. ornativentris, R. pirica, R. sakuraii, R. tagoi, and R. tsushimensis) are only incompletely understood. Cladograms based upon maximum parsimony analyses of the brevinin-1 and brevinin-2 amino acid sequences provide strong support for a sister-group relationship between R. dybowskii and R. pirica and somewhat weaker support for a sister-group relationship between R. okinavana and R. tsushimensis. These conclusions are consistent with previous analyses based upon allozyme variations and comparisons of the nucleotide sequences of mitochondrial genes.
|
| 17698251 |
Purification and characterization of antimicrobial peptides from the skin secretion of Rana dybowskii |
10.1016/j.peptides.2007.07.002. |
Peptides |
Purification and characterization of antimicrobial peptides from the skin secretion of Rana dybowskii
Abstract
- Six antimicrobial peptides designated dybowskins were isolated from the skin secretion of Rana dybowskii, an edible frog in Korea. Dybowskin-1 (FLIGMTHGLICLISRKC) and dybowskin-2 (FLIGMTQGLICLITRKC) were isoforms differing in only two amino acid residues at the 7th and 14th positions from the N-terminus, and they showed amino acid sequence similarities with ranalexin peptides. Dybowskin-3 (GLFDVVKGVLKGVGKNVAGSLLEQLKCKLSGGC), dybowskin-4 (VWPLGLVICKALKIC), dybowskin-5 (GLFSVVTGVLKAVGKNVAKNVGGSLLEQLKCKISGGC), and dybowskin-6 (FLPLLLAGLPLKLCFLFKKC) differed in both size and sequence, and they were, in terms of amino acid sequence similarities, related to brevinin-2, japonicin-2, esculentin-2, and brevinin-1 peptides, respectively. All the peptides presented in this paper contained Rana-box, the cyclic heptapeptide domain, which is conserved in other antimicrobial peptides derived from the genus Rana. All the dybowskin peptides showed a broad spectrum of antimicrobial activity against the Gram-positive and Gram-negative bacteria (minimum inhibition concentrations (MIC), 12.5 to >100 microg/ml) and against Candida albicans (MIC, 25 to >100 microg/ml). Especially, dybowskin-4 with valine at its N-terminus was the most abundant and showed the strongest antimicrobial activity among all the dybowskin peptides. This result indicates that the dybowskin peptides from R. dybowskii, whose main habitats are mountains or forests, have evolved differently from antimicrobial peptides isolated from other Korean frogs, whose habitats are plain fields.
|
| 17704056 |
Regulation of E2F1 function by the nuclear corepressor KAP1 |
10.1074/jbc.M704757200. |
J Biol Chem |
Regulation of E2F1 function by the nuclear corepressor KAP1
Abstract
- KAP1 is a nuclear corepressor with conserved domains for RING finger, B boxes, leucine zipper alpha helical coiled-coil region, plant homeo domain finger, and bromo domain. The plant homeo domain finger and bromo domain of KAP1 cooperatively function as a transcription repression domain by recruiting the histone deacetylase complex NuRD and histone H3 lysine 9-specific methyltransferase SETDB1. Here we report that KAP1 binds the E2F1 transcription factor in a retinoblastoma protein (pRb)-independent fashion and inhibits E2F1 activity. KAP1 stimulates formation of E2F1-HDAC1 complex and inhibits E2F1 acetylation. Ectopic expression of KAP1 represses E2F1 transcription and apoptosis functions independent of pRb. Depletion of endogenous KAP1 in pRb-deficient Saos2 cells by RNA interference increases E2F1 acetylation level, stimulates E2F1 transcriptional activity, and sensitizes apoptosis response to DNA damage. Therefore, KAP1 contributes to the negative regulation of E2F1 and may serve as a partial backup to prevent E2F1-mediated apoptosis in the absence of pRb.
|
| 17721928 |
Identification of the first germline mutation in the extracellular domain of the follitropin receptor responsible for spontaneous ovarian hyperstimulation syndrome |
10.1002/humu.20604. |
Hum Mutat |
Identification of the first germline mutation in the extracellular domain of the follitropin receptor responsible for spontaneous ovarian hyperstimulation syndrome
Abstract
- The receptors for follitropin (FSHR), thyrotropin (TSHR), and lutropin/chorionic gonadotropin (LHCGR) are the members of the glycoprotein hormone (GPH) receptors (GPHR) family. They present a bipartite structure with a large extracellular amino-terminal domain (ECD), responsible for high-affinity hormone binding, and a carboxyl-terminal serpentine region, implicated in transduction of the activation signal. Spontaneous ovarian hyperstimulation syndrome (sOHSS) is a rare genetic condition in which human chorionic gonadotropin (hCG) promiscuously stimulates the FSHR during the first trimester of pregnancy. Surprisingly, germline FSHR mutations responsible for the disease have so far been found only in the transmembrane helices of the serpentine region of the FSHR, outside the hormone binding domain. When tested functionally, all mutants were abnormally sensitive to both hCG and thyrotropin (TSH) while displaying constitutive activity. This loss of ligand specificity was attributed to the lowering of an intramolecular barrier of activation rather than to an increase of binding affinity. Here we report the first germline mutation responsible for sOHSS (c.383C>A, p.Ser128Tyr), located in the ECD of the FSHR. Contrary to the mutations described previously, the p.Ser128Tyr FSHR mutant displayed increase in affinity and sensitivity toward hCG and did not show any constitutive activity, nor promiscuous activation by TSH. Thus, sOHSS can be achieved from different molecular mechanisms involving each functional domains of the FSHR. Based on the structure of the FSHR/FSH complex and site-directed mutagenesis studies, we provide robust molecular models for the GPH/GPHR complexes and we propose a molecular explanation to the binding characteristics of the p.Ser128Tyr mutant.
|
| 17764786 |
A new family of antimicrobial peptides from skin secretions of Rana pleuraden |
10.1016/j.peptides.2007.07.020. |
Peptides |
A new family of antimicrobial peptides from skin secretions of Rana pleuraden
Abstract
- While conducting experiments to investigate antimicrobial peptides of amphibians living in the Yunnan-Guizhou region of southwest China, a new family of antimicrobial peptides was identified from skin secretions of the Yunnan frog, Rana pleuraden. Members of the new peptide family named pleurain-As are composed of 26 amino acids with a unique N-terminal sequence (SIIT) and a disulfide-bridged heptapeptide sequence (CRLYNTC). By BLAST search, pleurain-As had no significant similarity to any known peptides. Native and synthetic peptides showed antimicrobial activities against tested microorganisms including Gram-negative and Gram-positive bacteria and fungi. Twenty different cDNAs encoding pleurain-As were cloned from the skin cDNA library of R. pleuraden. The precursors of pleurain-As are composed of 69 amino acid residues including predicted signal peptides, acidic propieces, and cationic mature antimicrobial peptides. The preproregion of pleurain-A precursor comprises a hydrophobic signal peptide of 22 residues followed by an 18 residue acidic propiece which terminates by a typical prohormone processing signal Lys-Arg. The preproregions of precursors are very similar to other amphibian antimicrobial peptide precursors but the mature pleurain-As are different from other antimicrobial peptide families. The remarkable similarity of preproregions of precursors that give rise to very different antimicrobial peptides in distantly related frog species suggests that the corresponding genes form a multigene family originating from a common ancestor. Furthermore, pleurain-As could exert antimicrobial capability against Helicobacter pylori. This is the first report of naturally occurring peptides with anti-H. pylori activity from Rana amphibians.
|
| 17786427 |
Formation of cyclotides and variations in cyclotide expression in Oldenlandia affinis suspension cultures |
10.1007/s00253-007-1159-6. |
Appl Microbiol Biotechnol |
Formation of cyclotides and variations in cyclotide expression in Oldenlandia affinis suspension cultures
Abstract
- Cyclotides, a family of disulfide-rich mini-proteins, show a wide range of biological activities, making them interesting targets for pharmaceutical and agrochemical applications, but little is known about their natural function and the events that trigger their expression. An investigation of nutritional variations and irradiation during a batch process involving plant cell cultures has been performed, using the native African medical herb, Oldenlandia affinis, as a model plant. The results demonstrated the biosynthesis of kalata B1, the main cyclotide in O. affinis, in a combined growth/nongrowth-associated pattern. The highest concentration, 0.37 mg g(-1) dry weight, was accumulated in irradiated cells at 35 mumol m(-2) s(-1). Furthermore, 12 novel cyclotides were identified and the expression of various cyclotides compared in irradiated vs non-irradiated cultures. The results indicate that cyclotide expression varies greatly depending on physiological conditions and environmental stress. Kalata B1 is the most abundant cyclotide in plant suspension cultures, which underlies its importance as a natural defense molecule. The identification of novel cyclotides in suspension cultures, compared to whole plants, indicates that there may be more novel cyclotides to be discovered and that the genetic network regulating cyclotide expression is a very sensitive system, ready to adapt to the current environmental growth condition.
|
| 17786911 |
Numerical characterization of the conformation of cyclic peptides and its application |
10.1002/jcc.20744. |
J Comput Chem |
Numerical characterization of the conformation of cyclic peptides and its application
Abstract
- Many classes of functional cyclic peptide molecules are determined by experimental techniques, but few similarities of cyclic peptides are detectable. We propose three numerical characterizations of conformations of cyclic peptides. By incorporating the information on atomic coordinates of cyclic peptides, the coordinates are transformed into a characteristic sequence. Then we calculate its center of gravity, the eigenvalues of its Euclidean and L/L matrices, and regard them as descriptors to numerically characterize the conformations of cyclic peptides. Finally, the method is tested by analyzing the similarities of cyclic peptides presented in Table 1.
|
| 17804600 |
Are alpha9alpha10 nicotinic acetylcholine receptors a pain target for alpha-conotoxins? |
10.1124/mol.107.040568. |
Mol Pharmacol |
Are alpha9alpha10 nicotinic acetylcholine receptors a pain target for alpha-conotoxins?
Abstract
- The synthetic alpha-conotoxin Vc1.1 is a small disulfide bonded peptide currently in development as a treatment for neuropathic pain. Unlike Vc1.1, the native post-translationally modified peptide vc1a does not act as an analgesic in vivo in rat models of neuropathic pain. It has recently been proposed that the primary target of Vc1.1 is the alpha9alpha10 nicotinic acetylcholine receptor (nAChR). We show that Vc1.1 and its post-translationally modified analogs vc1a, [P6O]Vc1.1, and [E14gamma]Vc1.1 are equally potent at inhibiting ACh-evoked currents mediated by alpha9alpha10 nAChRs. This suggests that alpha9alpha10 nAChRs are unlikely to be the molecular mechanism or therapeutic target of Vc1.1 for the treatment of neuropathic pain.
|
| 17846173 |
Parkin-mediated K63-linked polyubiquitination targets misfolded DJ-1 to aggresomes via binding to HDAC6. |
10.1083/jcb.200611128 |
J. Cell Biol. |
Parkin-mediated K63-linked polyubiquitination targets misfolded DJ-1 to aggresomes via binding to HDAC6.
Abstract
- Sequestration of misfolded proteins into pericentriolar inclusions called aggresomes is a means that cells use to minimize misfolded protein-induced cytotoxicity. However, the molecular mechanism by which misfolded proteins are recruited to aggresomes remains unclear. Mutations in the E3 ligase parkin cause autosomal recessive Parkinson's disease that is devoid of Lewy bodies, which are similar to aggresomes. Here, we report that parkin cooperates with heterodimeric E2 enzyme UbcH13/Uev1a to mediate K63-linked polyubiquitination of misfolded DJ-1. K63-linked polyubiquitination of misfolded DJ-1 serves as a signal for interaction with histone deacetylase 6, an adaptor protein that binds the dynein-dynactin complex. Through this interaction, misfolded DJ-1 is linked to the dynein motor and transported to aggresomes. Furthermore, fibroblasts lacking parkin display deficits in targeting misfolded DJ-1 to aggresomes. Our findings reveal a signaling role for K63-linked polyubiquitination in dynein-mediated transport, identify parkin as a key regulator in the recruitment of misfolded DJ-1 to aggresomes, and have important implications regarding the biogenesis of Lewy bodies.
|
| 17872950 |
Critical and functional regulation of CHOP (C/EBP homologous protein) through the N-terminal portion. |
10.1074/jbc.m703735200 |
J. Biol. Chem. |
Critical and functional regulation of CHOP (C/EBP homologous protein) through the N-terminal portion.
Abstract
- C/EBP homologous protein (CHOP) is an endoplasmic reticulum stress-inducible protein that plays a critical role in the regulation of programmed cell death; however, the regulation of its function has not been well characterized. We have previously demonstrated that CHOP is regulated by the ubiquitin-proteasome system. In this study, during the process of clarifying the mechanism of the degradation of CHOP, we identified a novel regulation domain of CHOP in its N-terminal portion that is involved in various regulations and functions. The CHOP N-terminal domain is necessary not only for protein degradation but also for its transactivity and interaction with p300. In addition, trichostatin A, a histone deacetylase inhibitor, repressed the degradation of CHOP protein via the N-terminal domain. TRB3, a mammalian tribbles homolog that functions as a repressor of CHOP, also interacted with CHOP via the N-terminal portion and significantly blocked the association of p300 with CHOP. These
Results suggest that the N-terminal portion of CHOP plays a crucial role in its functional regulation and enable us to identify a novel function of TRB3 as an intracellular antagonist of the p300-binding domain of CHOP.
|
| 17878146 |
Polymyxin B for the treatment of multidrug-resistant pathogens: a critical review |
10.1093/jac/dkm357. |
J Antimicrob Chemother |
Polymyxin B for the treatment of multidrug-resistant pathogens: a critical review
Abstract
- Polymyxins have re-emerged in clinical practice owing to the dry antibiotic development pipeline and worldwide increasing prevalence of nosocomial infections caused by multidrug-resistant (MDR) Gram-negative bacteria. Polymyxin B and colistin (polymyxin E) have been ultimately considered as the last-resort treatment of such infections. Microbiological, pharmacokinetic, pharmacodynamic and clinical data available for polymyxin B are reviewed in this paper. Polymyxin B has rapid in vitro bactericidal activity against major MDR Gram-negative bacteria, such as Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae. Acquired resistance to this agent is still rare among these pathogens. However, optimized dosage regimens are not known yet. Good clinical outcomes have been observed in the majority of the patients treated with intravenous polymyxin B in recent studies. However, these studies failed to provide definitive conclusions due to limitations of study design and additional clinical trials are required. Although combination therapy may be an attractive option based on some currently available in vitro data, clinical data supporting such recommendations are lacking. Since polymyxins will be increasingly used for the treatment of infections caused by MDR bacteria, clinical pharmacokinetic, pharmacodynamic and toxicodynamic studies underpinning the optimal use of these drugs are urgently required.
|
| 17887724 |
ES-242 derivatives and cycloheptapeptides from Cordyceps sp. strains BCC 16173 and BCC 16176 |
10.1021/np070357h. |
J Nat Prod |
ES-242 derivatives and cycloheptapeptides from Cordyceps sp. strains BCC 16173 and BCC 16176
Abstract
- Five new ES-242 analogues ( 1- 5) were isolated together with nine known compounds ( 6- 14) from the insect pathogenic fungus Cordyceps sp. BCC 16173. A closely related strain, BCC 16176, provided cordyheptapeptide A ( 15) and small amount of its new analogue, cordyheptapeptide B ( 16), along with known ES-242s. Structures of the new bioxanthracenes, 1- 5, were determined to be 6'- O-desmethyl analogues of 6 (ES-242-4), 8, 9 (ES-242-2), 12, and 13, respectively, primarily by spectroscopic analyses. Cordyheptapeptide B ( 16) has an N-methyl- l-phenylalanine residue instead of the N-methyl- l-tyrosine in 15.
|
| 17910513 |
Lyngbyastatins 5-7, potent elastase inhibitors from Floridian marine cyanobacteria, Lyngbya spp |
10.1021/np0702436. |
J Nat Prod |
Lyngbyastatins 5-7, potent elastase inhibitors from Floridian marine cyanobacteria, Lyngbya spp
Abstract
- Three new analogues of dolastatin 13, termed lyngbyastatins 5-7 ( 1- 3), were isolated from two different collections of marine cyanobacteria, Lyngbya spp., from South Florida. Their planar structures were deduced by a combination of NMR techniques, and the absolute configurations were established by modified Marfey's analysis of the acid hydrolyzates. The related cyclodepsipeptide somamide B ( 4), previously reported from a Fijian cyanobacterium, has also been found in one of the extracts, and its absolute stereochemistry was unambiguously assigned for the first time. Compounds 1- 4 were found to selectively inhibit elastase over several other serine proteases, with IC50 values for porcine pancreatic elastase ranging from 3 to 10 nM.
|
| 17917241 |
Comparison of the bioactive secondary metabolites from the scale insect pathogens, Anamorph Paecilomyces cinnamomeus, and Teleomorph Torrubiella luteorostrata |
10.1038/ja.2007.73. |
J Antibiot (Tokyo) |
Comparison of the bioactive secondary metabolites from the scale insect pathogens, Anamorph Paecilomyces cinnamomeus, and Teleomorph Torrubiella luteorostrata
Abstract
- A scale insect pathogen Paecilomyces cinnamomeus BCC 9616 and its teleomorph Torrubiella luteorostrata BCC 9617, collected on the same host specimen, were fermented and chemically explored. Both fungi produced paecilodepsipeptide A (1) and zeorin (4) as major constituents of mycelia extracts. The culture broth extract of BCC 9616 provided a known diketopiperazine, terezine D (5), and a new xanthone glycoside, norlichexanthone-6-O-beta-(4-O-methylglucopyranoside) (6). On the other hand, the broth extract of BCC 9617 contained small amounts of a new naphthopyrone glycoside, rubrofusarin-6-O-beta-(4-O-methylglucopyranoside) (7) along with 5. Structures of the new compounds, 6 and 7, were elucidated by interpretation of NMR and mass spectroscopic data. The overall results demonstrated that the metabolite profiles of the cultured anamorph (BCC 9616) and teleomorph (BCC 9617) originating from the same host specimen resemble each other closely. The (1)H-NMR spectroscopic analysis of the culture extracts from other strains of P. cinnamomeus and T. luteorostrata revealed that zeorin is the most commonly occurring fermentation product of these fungi, whereas paecilodepsipeptide A was the metabolite specific to the particular isolate BCC 9616/BCC 9617.
|
