排序方式: 共有77条查询结果,搜索用时 15 毫秒
61.
Kassem Ghaddar Eva-Maria Krammer Natalija Mihajlovic Sylvain Brohée Bruno André Martine Prévost 《The Journal of biological chemistry》2014,289(10):7232-7246
Amino acid uptake in yeast cells is mediated by about 16 plasma membrane permeases, most of which belong to the amino acid-polyamine-organocation (APC) transporter family. These proteins display various substrate specificity ranges. For instance, the general amino acid permease Gap1 transports all amino acids, whereas Can1 and Lyp1 catalyze specific uptake of arginine and lysine, respectively. Although Can1 and Lyp1 have different narrow substrate specificities, they are close homologs. Here we investigated the molecular rules determining the substrate specificity of the H+-driven arginine-specific permease Can1. Using a Can1-Lyp1 sequence alignment as a guideline and a three-dimensional Can1 structural model based on the crystal structure of the bacterial APC family arginine/agmatine antiporter, we introduced amino acid substitutions liable to alter Can1 substrate specificity. We show that the single substitution T456S results in a Can1 variant transporting lysine in addition to arginine and that the combined substitutions T456S and S176N convert Can1 to a Lyp1-like permease. Replacement of a highly conserved glutamate in the Can1 binding site leads to variants (E184Q and E184A) incapable of any amino acid transport, pointing to a potential role for this glutamate in H+ coupling. Measurements of the kinetic parameters of arginine and lysine uptake by the wild-type and mutant Can1 permeases, together with docking calculations for each amino acid in their binding site, suggest a model in which residues at positions 176 and 456 confer substrate selectivity at the ligand-binding stage and/or in the course of conformational changes required for transport. 相似文献
62.
Schuetz F Ehlert K Ge Y Schneeweiss A Rom J Inzkirweli N Sohn C Schirrmacher V Beckhove P 《Cancer immunology, immunotherapy : CII》2009,58(6):887-900
Background Breast cancer patients frequently harbour tumour-reactive memory T cells in their bone marrow (BM) but not in the blood. After
reactivation ex-vivo these cells rejected autologous breast tumours in xenotransplanted mice demonstrating therapeutic potential
upon reactivation and mobilization into the blood. We conducted a clinical pilot study on metastasized breast cancer patients
to investigate if ex-vivo reactivation of tumour-reactive BM memory T cells and their adoptive transfer is feasible and increases
the frequencies of tumour-reactive T cells in the blood.
Methods The study protocol involved one transfusion of T cells which were reactivated in vitro with autologous dendritic cells pulsed
with lysate of MCF7 breast cancer cells as source of tumour antigens. Immunomonitoring included characterization of T cell
activation in vitro and of tumour-specific T cells in the blood by interferon (IFN)-γ ELISPOT assay, HLA-tetramers and antigen-induced
interleukin (IL)-4 secretion.
Results Twelve patients with pre-existing tumour-reactive BM memory T cells were included into the study. In all cases, the treatment
was feasible and well tolerated. Six patients (responders) showed by ELISPOT assay de-novo tumour antigen-specific, IFN-γ-secreting
T cells in the blood after 7 days. In contrast, non responders showed in the blood tumour antigen-induced IL-4 responses.
All responders received more than 6.5 × 103 tumour-reactive T cells. In contrast, all non responders received lower numbers of tumour antigen-reactive T cells. This
was associated with reduced activation of memory T cells in activation cultures, increased amounts of CD4+ CD25high regulatory T cells in the BM and increased tumour antigen-dependent IL-10 secretion. The latter was prevented by preceding
depletion of regulatory T cells suggesting that regulatory T cells in the BM can inhibit reactivation of tumour-specific T
cells.
Conclusion Taken together, adoptive transfer of ex-vivo re-stimulated tumour-reactive memory T cells from BM of metastasized breast cancer
patients can induce the presence of tumour antigen-reactive type-1 T cells in the peripheral blood.
Florian Schuetz and Katrin Ehlert contributed equally to the study. 相似文献
63.
64.
We have isolated the tryptophan auxotrophic mutant strain, PK101, of Pichia guilliermondii. This strain is not defective in any of the tryptophan biosynthetic enzymes, but its chrismate mutase, an enzyme of the phenylalanine-tyrosine biosynthesis, is changed. In comparison with the wild type chorismate mutase, the enzyme of PK101 is characterized by a complete loss of sensitivity to l-phenylalanine inhibition and to a considerable loss of sensitivity to l-tryptophan activation. Furthermore, the chorismate mutase activity of the mutant is more than 7-fold higher in the absence of l-tryptophan than in the wild type. The PK101 enzyme is also changed in the pH optimum and in some kinetic constants. We found an increased intracellular pool of both phenylalanine and tyrosine and a reduced contents of tryptophan in the mutant cells. Our genetic data indicate that the mutant phenotype is dominant over the wild type. 相似文献
65.
This study investigated infection levels with Fusarium graminearum and Fusarium culmorum in malt barley and wheat in eastern Croatia. The contamination was surveyed over three consecutive crop years (2001–2003) on five locations for barley and three wheat cultivating locations. F. graminearum loads reached levels of potentially serious threat for the commercial production of malting raw materials in both cereals (up to 29.1%). On the other hand, the mean percentage of kernels infected with F. culmorum was low to medium (up to 6.1%). The fungal invasions for years and locations were affected by meteorologic and other environmental factors and the pattern seemed to be consistent with species-specific optimal conditions reported by other authors. 相似文献
66.
Expression profiling in Medicago truncatula identifies more than 750 genes differentially expressed during nodulation, including many potential regulators of the symbiotic program 下载免费PDF全文
El Yahyaoui F Küster H Ben Amor B Hohnjec N Pühler A Becker A Gouzy J Vernié T Gough C Niebel A Godiard L Gamas P 《Plant physiology》2004,136(2):3159-3176
In this study, we describe a large-scale expression-profiling approach to identify genes differentially regulated during the symbiotic interaction between the model legume Medicago truncatula and the nitrogen-fixing bacterium Sinorhizobium meliloti. Macro- and microarrays containing about 6,000 probes were generated on the basis of three cDNA libraries dedicated to the study of root symbiotic interactions. The experiments performed on wild-type and symbiotic mutant material led us to identify a set of 756 genes either up- or down-regulated at different stages of the nodulation process. Among these, 41 known nodulation marker genes were up-regulated as expected, suggesting that we have identified hundreds of new nodulation marker genes. We discuss the possible involvement of this wide range of genes in various aspects of the symbiotic interaction, such as bacterial infection, nodule formation and functioning, and defense responses. Importantly, we found at least 13 genes that are good candidates to play a role in the regulation of the symbiotic program. This represents substantial progress toward a better understanding of this complex developmental program. 相似文献
67.
A Comparative Study of In Vitro Cytotoxic,Antioxidant, and Antimicrobial Activity of Pt(II), Zn(II), Cu(II), and Co(III) Complexes with N‐heteroaromatic Schiff Base (E)‐2‐[N′‐(1‐pyridin‐2‐yl‐ethylidene)hydrazino]acetate 下载免费PDF全文
Nenad R. Filipović Ivanka Marković Dragana Mitić Natalija Polović Miloš Milčić Marija Dulović Maja Jovanović Milena Savić Miomir Nikšić Katarina Anđelković Tamara Todorović 《Journal of biochemical and molecular toxicology》2014,28(3):99-110
In search for novel biologically active metal based compounds, an evaluation of in vitro cytotoxic, antioxidant, and antimicrobial activity of new Pt(II) complex and its Zn(II), Cu(II), and Co(III) analogues, with NNO tridentately coordinated N‐heteroaromatic Schiff base ligand (E)‐2‐[N′‐(1‐pyridin‐2‐yl‐ethylidene)hydrazino]acetate, was performed. Investigation of antioxidative properties showed that all of the compounds have strong radical scavenging potencies. The Zn(II) complex showed potent inhibition of DNA cleavage by hydroxyl radical. A cytotoxic action of investigated compounds was evaluated on cultures of human promyelocitic leukaemia (HL‐60), human glioma (U251), rat glioma (C6), and mouse melanoma (B16) cell lines. It was shown that binuclear pentacoordinated Zn(II) complex possesses a strong dose‐dependent cytotoxic activity, of the same order of magnitude as cisplatin on B16, C6, and U251 cells. Furthermore, Zn(II) complex causes oxidative stress‐induced apoptotic death of HL‐60 leukemic cells, associated with caspase activation, phosphatidylserine externalization, and DNA fragmentation. 相似文献
68.
Natalija Lukic Rémy Visentin Myriam Delhaye Jean-Louis Frossard Pierre Lescuyer Jean-Marc Dumonceau Annarita Farina 《Biochimica et Biophysica Acta - Proteins and Proteomics》2014,1844(5):1026-1033
Proteomics is a key tool in the identification of new bile biomarkers for differentiating malignant and nonmalignant biliary stenoses. Unfortunately, the complexity of bile and the presence of molecules interfering with protein analysis represent an obstacle for quantitative proteomic studies in bile samples. The simultaneous need to introduce purification steps and minimize the use of pre-fractionation methods inevitably leads to protein loss and limited quantifications. This dramatically reduces the chance of identifying new potential biomarkers. In the present study, we included differential centrifugation as a preliminary step in a quantitative proteomic workflow involving iTRAQ labeling, peptide fractionation by OFFGEL electrophoresis and LC-MS/MS, to compare protein expression in bile samples collected from patients with malignant or nonmalignant biliary stenoses. A total of 1267 proteins were identified, including a set of 322 newly described bile proteins, mainly belonging to high-density cellular fractions. The subsequent comparative analysis led to a 5-fold increase in the number of quantified proteins over previously published studies and highlighted 104 proteins overexpressed in malignant samples. Finally, immunoblot verifications performed on a cohort of 8 malignant (pancreatic adenocarcinoma, n = 4; cholangiocarcinoma, n = 4) and 5 nonmalignant samples (chronic pancreatitis, n = 3; biliary stones, n = 2) confirmed the results of proteomic analysis for three proteins: olfactomedin-4, syntenin-2 and Ras-related C3 botulinum toxin substrate 1. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge. 相似文献
69.
Marinković N Pasalić D Grsković B Ferencak G Honović L Rukavina AS 《Collegium antropologicum》2008,32(3):725-729
Increased serum bilirubin levels in patients with Gilbert syndrome (GS) are caused by reduction of hepatic activity of bilirubin glucuronosyltranferase to about 30% of normal. UGT1A1 genetic polymorphism with absent or very low bilirubin UDP-glucuronosyltransferase (B-UGT) activity is associated with Gilbert's syndrome (GS) and other hyperbilirubinemias. The genetic basis of GS is the insertion of two additional TA nucleotides (resulting in seven repeats of TA) in the TATAA box, present in proximal promoter of UGT1A1 gene. This study included 323 Croatian pre-scholars, including 164 boys and 159 girls. Statistical analysis showed significant difference for total bilirubin concentration between different genotypes (p < 0.001). Also, statistically significant difference for total bilirubin concentration was emphasized between genotypes 6/6 and 7/7 (p < 0.001) as well as 6/7 and 7/7 (p < 0.001). Higher total plasma bilirubin concentrations are significantly correlated with 7/7 genotype which is present in 9.8% of population studied. 相似文献
70.
Tamara Paff Niki T. Loges Isabella Aprea Kaman Wu Zeineb Bakey Eric G. Haarman Johannes M.A. Daniels Erik A. Sistermans Natalija Bogunovic Gerard W. Dougherty Inga M. Höben Jörg Große-Onnebrink Anja Matter Heike Olbrich Claudius Werner Gerard Pals Miriam Schmidts Heymut Omran Dimitra Micha 《American journal of human genetics》2017,100(1):160-168