|
|
By admin, on May 16th, 2012
Vet Microbiol. 2012 Apr 25;
Xiong L, Ling J, Gao Q, Zhou Y, Li T, Gao S, Liu X
Aerobactin counts for much to the pathogenesis of avian pathogenic Escherichia coli (APEC), iutA is responsible for the expression of a specific outer membrane receptor protein for ferric aerobactin, and iucB is involved in the aerobactin synthesis. To our knowledge, the contribution of iucB to the pathogenicity of APEC has not been assessed till now. In this study, the mutants E058ΔiucB and E058ΔiucBΔiutA were constructed and characterized. There were no differences observed in a series of tests including the embryo lethality, invasion assay in HD11 cells and the ability to survive in SPF chicken serum. Meanwhile, the mutants showed decreased pathogenicity as compared with the wild-type strain through a series of experiments in vivo. The mutants E058ΔiucB and E058ΔiucBΔiutA greatly reduced in all of the tested tissues in vivo persistence (p<0.001). In the meantime, the mutants had no ability to produce aerobactin. Reintroduction of the iucB gene on a multicopy expression plasmid pGEX-6p-1 restored the capacity to produce aerobactin as similar to that of wild-type strain E058. The results indicated that the iucB gene related virulence factors including the iron assimilation system were important for the pathogenesis of APEC E058. As showed in the in vivo competition assay, compared to the parental strain E058, E058ΔiucB had a significant reduction of bacterial loads in heart (p<0.01), liver (p<0.01), kidney (p<0.01), spleen (p<0.05) and lung (p<0.05), respectively, while E058ΔiucBΔiutA had a sharp reduction in all of the five tissues to be tested (p<0.001). These results suggested that the single gene either iucB or iutA was likely to be involved directly or indirectly in iron uptake for the pathogenicity of APEC E058, and there was an obviously synergistic effect between iucB and iutA genes on the pathogenicity of APEC E058.
See the original post here:
Construction of iucB and iucBiutA mutants of avian pathogenic Escherichia coli and evaluation of their pathogenicity.
By admin, on May 14th, 2012
Comp Biochem Physiol A Mol Integr Physiol. 2012 May 2;
Notch EG, Chapline C, Flynn E, Lameyer T, Lowell A, Sato D, Shaw JR, Stanton BA
The Atlantic killifish (Fundulus heteroclitus) is an environmental sentinel organism used extensively for studies of environmental toxicants and osmoregulation. Previous research in our laboratory has shown that acute acclimation to seawater is mediated by an increase in SGK1. SGK1 promotes the trafficking of CFTR chloride channels from intracellular vesicles to the plasma membrane of the gill within the first hour in seawater resulting in increased chloride secretion. Although we have shown that the increase in gill SGK1 does not require activation of the glucocorticoid receptor, the mechanisms that mediate the rise SGK1 during acute acclimation is unknown. To test the hypothesis that mitogen activated protein kinase (MAPK14) is responsible for the rise in SGK1 we identified the coding sequence of killifish MAPK14-1 and designed a translational blocking vivo-morpholino targeting MAPK14-1. Injection of the MAPK14-1 vivo-morpholino resulted in a 30% reduction of MAPK14-1 and a 45% reduction in phosphorylated-MAPK14-1 protein in the gill of killifish transitioned from freshwater to seawater. Knock down of phosphorlyated-MAPK14-1 completely blocked the rise in SGK1 mRNA and protein in the killifish gill, providing the first direct and in vivo evidence that MAPK14-1 is necessary for acute seawater acclimation.
Read more from the original source:
Mitogen activated protein kinase 14-1 regulates serum glucocorticoid kinase 1 during seawater acclimation in Atlantic killifish, Fundulus heteroclitus.
By admin, on May 14th, 2012
Comp Biochem Physiol A Mol Integr Physiol. 2012 May 2;
Notch EG, Chapline C, Flynn E, Lameyer T, Lowell A, Sato D, Shaw JR, Stanton BA
The Atlantic killifish (Fundulus heteroclitus) is an environmental sentinel organism used extensively for studies of environmental toxicants and osmoregulation. Previous research in our laboratory has shown that acute acclimation to seawater is mediated by an increase in SGK1. SGK1 promotes the trafficking of CFTR chloride channels from intracellular vesicles to the plasma membrane of the gill within the first hour in seawater resulting in increased chloride secretion. Although we have shown that the increase in gill SGK1 does not require activation of the glucocorticoid receptor, the mechanisms that mediate the rise SGK1 during acute acclimation is unknown. To test the hypothesis that mitogen activated protein kinase (MAPK14) is responsible for the rise in SGK1 we identified the coding sequence of killifish MAPK14-1 and designed a translational blocking vivo-morpholino targeting MAPK14-1. Injection of the MAPK14-1 vivo-morpholino resulted in a 30% reduction of MAPK14-1 and a 45% reduction in phosphorylated-MAPK14-1 protein in the gill of killifish transitioned from freshwater to seawater. Knock down of phosphorlyated-MAPK14-1 completely blocked the rise in SGK1 mRNA and protein in the killifish gill, providing the first direct and in vivo evidence that MAPK14-1 is necessary for acute seawater acclimation.
Read the original:
Mitogen activated protein kinase 14-1 regulates serum glucocorticoid kinase 1 during seawater acclimation in Atlantic killifish, Fundulus heteroclitus.
By admin, on May 14th, 2012
Fas antigen and Apo-1 antigen, is a type I transmembrane protein, tumor necrosis factor (Tumor Necrosis Factor, TNF) and nerve growth factor receptor superfamily.Fas L is a type II membrane protein, also belong to the family …
See original here:
unimaxunews.com – and nerve growth factor receptor superfamily …
By admin, on May 14th, 2012
Fas antigen and Apo-1 antigen, is a type I transmembrane protein, tumor necrosis factor (Tumor Necrosis Factor, TNF) and nerve growth factor receptor superfamily.Fas L is a type II membrane protein, also belong to the family …
Go here to see the original:
unimaxunews.com – and nerve growth factor receptor superfamily …
By admin, on May 13th, 2012
J Biomol Struct Dyn. 2012 Feb; 30(1): 30-44
Xu J, Xu J, Chen H
MT7 is a selective human muscarinic acetylcholine receptor 1 (hM1) allosteric binder with subnanomolar affinity. Understanding the binding mode of hM1-MT7 will give insights to discover small molecular ligand for hM1. MT7 is a peptide, and hM1 is a G-protein-coupled membrane receptor. Therefore, we have employed homology modeling, protein-protein docking, explicit membrane molecular dynamics (MD) simulations, and molecular mechanic/Poisson-Boltzmann surface area energy decomposition analysis approaches to reveal the hM1-MT7 binding mode. The binding mode is consistent with the experimental data. We have discovered that the binding mode consists of three interaction regions in five residue interaction clusters. By analyzing the cluster representative structures, the cluster residues form an interaction network, which shows a multiple-point-to-site binding mode. Hydrogen binding statistical analysis reveals that E170 (hM1) and R34 (MT7) are both locked in electrostatic cages with counter charges, respectively. This is confirmed by the dynamic distances calculation between these residues, and biological mutant experiments.
View original post here:
Interpreting the structural mechanism of action for MT7 and human muscarinic acetylcholine receptor 1 complex by modeling protein-protein interaction.
By admin, on May 13th, 2012
J Biomol Struct Dyn. 2012 Feb; 30(1): 30-44
Xu J, Xu J, Chen H
MT7 is a selective human muscarinic acetylcholine receptor 1 (hM1) allosteric binder with subnanomolar affinity. Understanding the binding mode of hM1-MT7 will give insights to discover small molecular ligand for hM1. MT7 is a peptide, and hM1 is a G-protein-coupled membrane receptor. Therefore, we have employed homology modeling, protein-protein docking, explicit membrane molecular dynamics (MD) simulations, and molecular mechanic/Poisson-Boltzmann surface area energy decomposition analysis approaches to reveal the hM1-MT7 binding mode. The binding mode is consistent with the experimental data. We have discovered that the binding mode consists of three interaction regions in five residue interaction clusters. By analyzing the cluster representative structures, the cluster residues form an interaction network, which shows a multiple-point-to-site binding mode. Hydrogen binding statistical analysis reveals that E170 (hM1) and R34 (MT7) are both locked in electrostatic cages with counter charges, respectively. This is confirmed by the dynamic distances calculation between these residues, and biological mutant experiments.
Follow this link:
Interpreting the structural mechanism of action for MT7 and human muscarinic acetylcholine receptor 1 complex by modeling protein-protein interaction.
By admin, on May 10th, 2012
Dalton Trans. 2012 Jun 7; 41(21): 6419-30
Winter PW, Al-Qatati A, Wolf-Ringwall AL, Schoeberl S, Chatterjee PB, Barisas BG, Roess DA, Crans DC
The effects of treatment with bis(maltolato)oxovanadium(iv) (BMOV) on protein localization in membrane microdomains were investigated by comparing the effects of insulin and treatment with BMOV on the lateral motions and compartmentalization of individual insulin receptors (IR). In addition, effects of insulin and BMOV on the association of IR, phosphorylated IR (pIR) and phosphorylated insulin receptor substrate-1 (pIRS-1) with chemically-isolated plasma membrane microdomains on rat basophilic leukemia (RBL-2H3) cells were evaluated. Single particle tracking experiments indicate that individual quantum dot-labeled IR on RBL-2H3 cells exhibit relatively unrestricted lateral diffusion of approximately 1 × 10(-10) cm(2) s(-1) and are confined in approximately 475 nm diameter cell-surface membrane compartments. After treating of RBL-2H3 cells with 10 μM BMOV, IR lateral diffusion and the size of IR-containing membrane compartments is significantly reduced to 6 × 10(-11) cm(2) s(-1) and approximately 400 nm, respectively. BMOV treatment also increases the association of IR with low-density, detergent-resistant membrane fragments isolated using isopycnic sucrose-gradient centrifugation from 2.4% for untreated cells to 25.8% for cells treated with 10 μM BMOV. Additionally, confocal fluorescence microscopic imaging of live RBL-2H3 cells labeled with the phase sensitive aminonaphthylethenylpyridinium-based dye, Di-4-ANEPPDHQ, indicates that BMOV treatment, but not insulin treatment, decreases cell-surface plasma membrane lipid order while fluorescence correlation spectroscopy measurements suggest that BMOV treatment does not affect IR surface-density or insulin binding affinity. Finally, model studies using microemulsions of cetyltrimethylammonium bromide (CTAB) micelles and (1)H NMR spectroscopy show that an oxidized form of BMOV readily localizes near the CTAB head-groups at the lipid-water interface. These observations were supported by IR spectroscopic studies using microemulsions of CTAB reverse micelles showing that both BMOV and oxidized BMOV are associated with the water pool. This conclusion is based on changes in (1)H NMR chemical shifts observed for the complex, oxidized BMOV. Moreover, these shifts appeared to be informative about the location of the complex. No differences were observed in the OD absorption peak positions for the CTAB reverse micelles prepared in the presence and absence of BMOV, oxidized BMOV or maltol. Combined, these results suggest that activation of IR signaling by both insulin and BMOV treatment involves increased association of IR with specialized, nanoscale membrane microdomains. The observed insulin-like activity of BMOV or decomposition products of BMOV may be due to changes in cell-surface membrane lipid order rather than due to direct interactions with IR.
Read the original post:
The anti-diabetic bis(maltolato)oxovanadium(iv) decreases lipid order while increasing insulin receptor localization in membrane microdomains.
By admin, on May 10th, 2012
Dalton Trans. 2012 Jun 7; 41(21): 6419-30
Winter PW, Al-Qatati A, Wolf-Ringwall AL, Schoeberl S, Chatterjee PB, Barisas BG, Roess DA, Crans DC
The effects of treatment with bis(maltolato)oxovanadium(iv) (BMOV) on protein localization in membrane microdomains were investigated by comparing the effects of insulin and treatment with BMOV on the lateral motions and compartmentalization of individual insulin receptors (IR). In addition, effects of insulin and BMOV on the association of IR, phosphorylated IR (pIR) and phosphorylated insulin receptor substrate-1 (pIRS-1) with chemically-isolated plasma membrane microdomains on rat basophilic leukemia (RBL-2H3) cells were evaluated. Single particle tracking experiments indicate that individual quantum dot-labeled IR on RBL-2H3 cells exhibit relatively unrestricted lateral diffusion of approximately 1 × 10(-10) cm(2) s(-1) and are confined in approximately 475 nm diameter cell-surface membrane compartments. After treating of RBL-2H3 cells with 10 μM BMOV, IR lateral diffusion and the size of IR-containing membrane compartments is significantly reduced to 6 × 10(-11) cm(2) s(-1) and approximately 400 nm, respectively. BMOV treatment also increases the association of IR with low-density, detergent-resistant membrane fragments isolated using isopycnic sucrose-gradient centrifugation from 2.4% for untreated cells to 25.8% for cells treated with 10 μM BMOV. Additionally, confocal fluorescence microscopic imaging of live RBL-2H3 cells labeled with the phase sensitive aminonaphthylethenylpyridinium-based dye, Di-4-ANEPPDHQ, indicates that BMOV treatment, but not insulin treatment, decreases cell-surface plasma membrane lipid order while fluorescence correlation spectroscopy measurements suggest that BMOV treatment does not affect IR surface-density or insulin binding affinity. Finally, model studies using microemulsions of cetyltrimethylammonium bromide (CTAB) micelles and (1)H NMR spectroscopy show that an oxidized form of BMOV readily localizes near the CTAB head-groups at the lipid-water interface. These observations were supported by IR spectroscopic studies using microemulsions of CTAB reverse micelles showing that both BMOV and oxidized BMOV are associated with the water pool. This conclusion is based on changes in (1)H NMR chemical shifts observed for the complex, oxidized BMOV. Moreover, these shifts appeared to be informative about the location of the complex. No differences were observed in the OD absorption peak positions for the CTAB reverse micelles prepared in the presence and absence of BMOV, oxidized BMOV or maltol. Combined, these results suggest that activation of IR signaling by both insulin and BMOV treatment involves increased association of IR with specialized, nanoscale membrane microdomains. The observed insulin-like activity of BMOV or decomposition products of BMOV may be due to changes in cell-surface membrane lipid order rather than due to direct interactions with IR.
Read more:
The anti-diabetic bis(maltolato)oxovanadium(iv) decreases lipid order while increasing insulin receptor localization in membrane microdomains.
By admin, on May 10th, 2012
and develop analytical methods for peptides and proteins, membrane spanning proteins, and receptor binding proteins. Candidate must possess a complete understanding of HPLC methods including normal and reverse-phase chromatography, Gel…
Read more here:
Analytical Methods Development Scientist – Peptides & Proteins at Dmc (Quincy, MA)
By admin, on May 10th, 2012
and develop analytical methods for peptides and proteins, membrane spanning proteins, and receptor binding proteins. Candidate must possess a complete understanding of HPLC methods including normal and reverse-phase chromatography, Gel…
Read more here:
Analytical Methods Development Scientist – Peptides & Proteins at Dmc (Quincy, MA)
By admin, on May 10th, 2012
methods for: *** Peptides and proteins *** Membrane spanning proteins *** Receptor binding proteins Candidate must possess at least 3 years performing similar duties in a pharmaceutical environment and a complete…
Read more here:
Analytical Method Development Chemist – Peptides & Proteins at Dmc (Nashua, NH)
By admin, on May 9th, 2012
PLoS One. 2012; 7(5): e36583
Pasco MY, Léopold P
In multicellular organisms, insulin/IGF signaling (IIS) plays a central role in matching energy needs with uptake and storage, participating in functions as diverse as metabolic homeostasis, growth, reproduction and ageing. In mammals, this pleiotropy of action relies in part on a dichotomy of action of insulin, IGF-I and their respective membrane-bound receptors. In organisms with simpler IIS, this functional separation is questionable. In Drosophila IIS consists of several insulin-like peptides called Dilps, activating a unique membrane receptor and its downstream signaling cascade. During larval development, IIS is involved in metabolic homeostasis and growth. We have used feeding conditions (high sugar diet, HSD) that induce an important change in metabolic homeostasis to monitor possible effects on growth. Unexpectedly we observed that HSD-fed animals exhibited severe growth inhibition as a consequence of peripheral Dilp resistance. Dilp-resistant animals present several metabolic disorders similar to those observed in type II diabetes (T2D) patients. By exploring the molecular mechanisms involved in Drosophila Dilp resistance, we found a major role for the lipocalin Neural Lazarillo (NLaz), a target of JNK signaling. NLaz expression is strongly increased upon HSD and animals heterozygous for an NLaz null mutation are fully protected from HSD-induced Dilp resistance. NLaz is a secreted protein homologous to the Retinol-Binding Protein 4 involved in the onset of T2D in human and mice. These results indicate that insulin resistance shares common molecular mechanisms in flies and human and that Drosophila could emerge as a powerful genetic system to study some aspects of this complex syndrome.
Continue reading here:
High sugar-induced insulin resistance in Drosophila relies on the lipocalin neural lazarillo.
By admin, on May 9th, 2012
Curr Opin Pharmacol. 2012 May 4;
Markiv A, Rambaruth ND, Dwek MV
Nearly all proteins are modified in post translational events, indeed, understanding the control and function of post translational modifications (PTMs) is arguably the 'next frontier' for cancer cell biologists. The most well understood PTMs include glycosylation, phosphorylation, ubiquitination, methylation and palmitylation. Each of these modifications has been observed to be altered in cancer, affecting key cellular pathways including signal transduction, cell membrane receptor function, and protein-protein interactions. A number of strategies have been proposed that aim to target the modified proteins themselves, the enzymes that construct them, or that boost host-cellular immunity against modified residues aberrantly expressed in cancer.
Visit link:
Beyond the genome and proteome: targeting protein modifications in cancer.
By admin, on May 9th, 2012
Curr Opin Pharmacol. 2012 May 4;
Markiv A, Rambaruth ND, Dwek MV
Nearly all proteins are modified in post translational events, indeed, understanding the control and function of post translational modifications (PTMs) is arguably the 'next frontier' for cancer cell biologists. The most well understood PTMs include glycosylation, phosphorylation, ubiquitination, methylation and palmitylation. Each of these modifications has been observed to be altered in cancer, affecting key cellular pathways including signal transduction, cell membrane receptor function, and protein-protein interactions. A number of strategies have been proposed that aim to target the modified proteins themselves, the enzymes that construct them, or that boost host-cellular immunity against modified residues aberrantly expressed in cancer.
Read this article:
Beyond the genome and proteome: targeting protein modifications in cancer.
By admin, on May 9th, 2012
Nature. 2012 Mar 29; 483(7391): 627-31
Reinhardt C, Bergentall M, Greiner TU, Schaffner F, Ostergren-Lundén G, Petersen LC, Ruf W, Bäckhed F
The gut microbiota is a complex ecosystem that has coevolved with host physiology. Colonization of germ-free (GF) mice with a microbiota promotes increased vessel density in the small intestine, but little is known about the mechanisms involved. Tissue factor (TF) is the membrane receptor that initiates the extrinsic coagulation pathway, and it promotes developmental and tumour angiogenesis. Here we show that the gut microbiota promotes TF glycosylation associated with localization of TF on the cell surface, the activation of coagulation proteases, and phosphorylation of the TF cytoplasmic domain in the small intestine. Anti-TF treatment of colonized GF mice decreased microbiota-induced vascular remodelling and expression of the proangiogenic factor angiopoietin-1 (Ang-1) in the small intestine. Mice with a genetic deletion of the TF cytoplasmic domain or with hypomorphic TF (F3) alleles had a decreased intestinal vessel density. Coagulation proteases downstream of TF activate protease-activated receptor (PAR) signalling implicated in angiogenesis. Vessel density and phosphorylation of the cytoplasmic domain of TF were decreased in small intestine from PAR1-deficient (F2r(-/-)) but not PAR2-deficient (F2rl1(-/-)) mice, and inhibition of thrombin showed that thrombin-PAR1 signalling was upstream of TF phosphorylation. Thus, the microbiota-induced extravascular TF-PAR1 signalling loop is a novel pathway that may be modulated to influence vascular remodelling in the small intestine.
View original post here:
Tissue factor and PAR1 promote microbiota-induced intestinal vascular remodelling.
|
