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91.
Solution structure of ribosomal protein S28E from Methanobacterium thermoautotrophicum 总被引:2,自引:0,他引:2 下载免费PDF全文
Wu B Yee A Pineda-Lucena A Semesi A Ramelot TA Cort JR Jung JW Edwards A Lee W Kennedy M Arrowsmith CH 《Protein science : a publication of the Protein Society》2003,12(12):2831-2837
The ribosomal protein S28E from the archaeon Methanobacterium thermoautotrophicum is a component of the 30S ribosomal subunit. Sequence homologs of S28E are found only in archaea and eukaryotes. Here we report the three-dimensional solution structure of S28E by NMR spectroscopy. S28E contains a globular region and a long C-terminal tail protruding from the core. The globular region consists of four antiparallel beta-strands that are arranged in a Greek-key topology. Unique features of S28E include an extended loop L2-3 that folds back onto the protein and a 12-residue charged C-terminal tail with no regular secondary structure and greater flexibility relative to the rest of the protein. The structural and surface resemblance to OB-fold family of proteins and the presence of highly conserved basic residues suggest that S28E may bind to RNA. A broad positively charged surface extending over one side of the beta-barrel and into the flexible C terminus may present a putative binding site for RNA. 相似文献
92.
Toll-like receptor 3 mediates a more potent antiviral response than Toll-like receptor 4 总被引:13,自引:0,他引:13
Doyle SE O'Connell R Vaidya SA Chow EK Yee K Cheng G 《Journal of immunology (Baltimore, Md. : 1950)》2003,170(7):3565-3571
We have recently described an IFN regulatory factor 3-mediated antiviral gene program that is induced by both Toll-like receptor (TLR)3 and TLR4 ligands. In our current study, we show that activation of IFN/viral response gene expression in primary macrophage cells is stronger and prolonged with TLR3 stimulation compared with that of TLR4. Our data also reveal that the cytoplasmic tails of both TLR3 and TLR4 can directly interact with myeloid differentiation factor 88 (MyD88). However, although Toll/IL-1 receptor homology domain-containing adaptor protein/MyD88 adaptor-like is able to associate with TLR4, we were unable to detect any interaction between Toll/IL-1 receptor homology domain-containing adaptor protein/MyD88 adaptor-like and TLR3. By using quantitative real-time PCR assays, we found that TLR3 expression is inducible by both TLR3 and TLR4 ligands, while TLR4 expression is not inducible by these same stimuli. Furthermore, using cells derived from mice deficient in the IFN-alphabetaR, we show that both TLR3 and TLR4 require IFN-beta autocrine/paracrine feedback to induce TLR3 expression and activate/enhance genes required for antiviral activity. More specifically, a subset of antiviral genes is initially induced independent of IFN-beta, yet the cytokine further enhances expression at later time points. This was in contrast to a second set of genes (including TLR3) that is induced only after IFN-beta production. Taken together, our data argue that, despite both TLR3 and TLR4 being able to use IFN-beta to activate/enhance antiviral gene expression, TLR3 uses multiple mechanisms to enhance and sustain the antiviral response more strongly than TLR4. 相似文献
93.
Kuo MR Morbidoni HR Alland D Sneddon SF Gourlie BB Staveski MM Leonard M Gregory JS Janjigian AD Yee C Musser JM Kreiswirth B Iwamoto H Perozzo R Jacobs WR Sacchettini JC Fidock DA 《The Journal of biological chemistry》2003,278(23):20851-20859
Tuberculosis and malaria together result in an estimated 5 million deaths annually. The spread of multidrug resistance in the most pathogenic causative agents, Mycobacterium tuberculosis and Plasmodium falciparum, underscores the need to identify active compounds with novel inhibitory properties. Although genetically unrelated, both organisms use a type II fatty-acid synthase system. Enoyl acyl carrier protein reductase (ENR), a key type II enzyme, has been repeatedly validated as an effective antimicrobial target. Using high throughput inhibitor screens with a combinatorial library, we have identified two novel classes of compounds with activity against the M. tuberculosis and P. falciparum enzyme (referred to as InhA and PfENR, respectively). The crystal structure of InhA complexed with NAD+ and one of the inhibitors was determined to elucidate the mode of binding. Structural analysis of InhA with the broad spectrum antimicrobial triclosan revealed a unique stoichiometry where the enzyme contained either a single triclosan molecule, in a configuration typical of other bacterial ENR:triclosan structures, or harbored two triclosan molecules bound to the active site. Significantly, these compounds do not require activation and are effective against wild-type and drug-resistant strains of M. tuberculosis and P. falciparum. Moreover, they provide broader chemical diversity and elucidate key elements of inhibitor binding to InhA for subsequent chemical optimization. 相似文献
94.
G3 domains of aggrecan and PG-M/versican form intermolecular disulfide bonds that stabilize cell-matrix interaction 总被引:3,自引:0,他引:3
The extracellular matrix plays a critical role in maintaining tissue integrity. Among the matrix molecules, the large aggregating chondroitin sulfate proteoglycans are the major structural molecules and are the primary contributors to the stability for some tissues such as cartilage. The notable exceptions are nanomelic cartilage and arthritic cartilage: the former contains a point mutation leading to a stop codon before translating to the C-terminal G3 domain; the latter contains a large proportion of aggrecan from which the G3 domain has been cleaved. These phenomena suggest that the G3 domain may be important in cartilage stability. Here, we demonstrated for the first time that the G3 domains of aggrecan and another proteoglycan, PG-M/versican, formed intermolecular disulfide bonds, and all subdomains were involved. Further studies indicated that each of the 10 cysteine residues of the aggrecan G3 domain could potentially form intermolecular disulfide bonds in vitro. The disulfide bonds were disrupted in the presence of reducing reagent beta-mercaptoethanol and dithiothreitol. As a result, normal chondrocyte-matrix interaction was disrupted, and the structure of the extracellular matrix was altered. Furthermore, disruption of disulfide bonds also reduced the role of PG-M/versican G3 domain in mediating cell adhesion. Our study provides strong evidence of the importance of proteoglycan interactions through intermolecular disulfide bonds in cartilage firmness and cell-matrix stability. 相似文献
95.
96.
Carlisle R Rhoads CA Aw TY Harrison L 《American journal of physiology. Cell physiology》2002,283(6):C1675-C1686
Human umbilical vein endothelial cells (HUVECs) are an endothelial model of replicative senescence. Oxidative stress, possibly due to dysfunctional mitochondria, is believed to play a key role in replicative senescence and atherosclerosis, an age-related vascular disease. In this study, we determined the effect of cell division on genomic instability, mitochondrial function, and redox status in HUVECs that were able to replicate for approximately 60 cumulative population doublings (CPD). After 20 CPD, the nuclear genome deteriorated and the protein content of the cell population increased. This indicated an increase in cell size, which was accompanied by an increase in oxygen consumption, ATP production, and mitochondrial genome copy number and approximately 10% increase in mitochondrial mass. The antioxidant capacity increased, as seen by an increase in reduced glutathione, glutathione peroxidase, GSSG reductase, and glucose-6-phosphate dehydrogenase. However, by CPD 52, the latter two enzymes decreased, as well as the ratio of mitochondrial-to-nuclear genome copies, the mitochondrial mass, and the oxygen consumption per milligram of protein. Our results signify that HUVECs maintain a highly reducing (GSH) environment as they replicate despite genomic instability and loss of mitochondrial function. 相似文献
97.
Su P Jury K Allison GE Wong WY Kim WS Liu CQ Vancov T Dunn NW 《FEMS microbiology letters》2002,216(1):43-47
Marine sponges frequently contain a complex mixture of bacteria, fungi, unicellular algae and cyanobacteria. Epifluorescent microscopy showed that Mycale (Carmia) hentscheli contained coccoid cyanobacteria. The 16S rRNA gene was amplified, fragments cloned and analysed using amplified rRNA gene restriction analysis. The nearly complete 16S rRNA gene of distinct clones was sequenced and aligned using ARB. The phylogenetic analysis indicated the presence of four closely related clones which have a high (8%) sequence divergence from known cyanobacteria, Cyanobacterium stanieri being the closest, followed by Prochloron sp. and Synechocystis sp. All belong to the order Chroococcales. The lack of non-molecular evidence prevents us from proposing a new genus. 相似文献
98.
Interaction of the heart-specific LIM domain protein, FHL2, with DNA-binding nuclear protein, hNP220 总被引:3,自引:0,他引:3
Ng EK Chan KK Wong CH Tsui SK Ngai SM Lee SM Kotaka M Lee CY Waye MM Fung KP 《Journal of cellular biochemistry》2002,84(3):556-566
Using a yeast two-hybrid library screen, we have identified that the heart specific FHL2 protein, four-and-a-half LIM protein 2, interacted with human DNA-binding nuclear protein, hNP220. Domain studies by the yeast two-hybrid interaction assay revealed that the second LIM domain together with the third and the fourth LIM domains of FHL2 were responsible to the binding with hNP220. Using green fluorescent protein (GFP)-FHL2 and blue fluorescent protein (BFP)-hNP220 fusion proteins co-expressed in the same cell, we demonstrated a direct interaction between FHL2 and hNP220 in individual nucleus by two-fusion Fluorescence Resonance Energy Transfer (FRET) assay. Besides, Western blot analysis using affinity-purified anti-FHL2 antipeptide antibodies confirmed a 32-kDa protein of FHL2 in heart only. Virtually no expression of FHL2 protein was detected in brain, liver, lung, kidney, testis, skeletal muscle, and spleen. Moreover, the expression of FHL2 protein was also detectable in the human diseased heart tissues. Our results imply that FHL2 protein can shuttle between cytoplasm and nucleus and may act as a molecular adapter to form a multicomplex with hNP220 in the nucleus, thus we speculate that FHL2 may be particularly important for heart muscle differentiation and the maintenance of the heart phenotype. 相似文献
99.
Indole-3-acetic acid metabolism in Lemna gibba undergoes dynamic changes in response to growth temperature 下载免费PDF全文
Auxin is the mobile signal controlling the rate of growth and specific aspects of the development of plants. It has been known for over a century that auxins act as the messenger linking plant development to specific environmental changes. An often overlooked aspect of how this is accomplished is the effect of the environment on metabolism of the major plant auxin, indole-3-acetic acid (IAA). We have studied the metabolism of IAA in relation to one environmental variable, growth temperature. The model system used was an inbred line of the aquatic monocot Lemna gibba G-3, 3F7-11 grown at temperatures ranging from 5 degrees C to 35 degrees C. IAA levels, the rate of IAA turnover, and the patterns of label incorporation from IAA precursors were measured using stable isotope-mass spectrometric techniques and were evaluated relative to growth at the experimental temperatures. IAA levels exhibited unusually high variability in plants grown at 15 degrees C and 20 degrees C. Turnover rates were quite rapid throughout the range of experimental temperatures except at 25 degrees C, where IAA turnover was notably slower. These results suggest that a transition occurred over these temperatures for some aspect of IAA metabolism. Analysis of [(15)N]anthranilate and [(2)H(5)]tryptophan (Trp) incorporation into IAA showed that Trp-dependent biosynthesis predominated at 15 degrees C; however, Trp-independent biosynthesis of IAA was the major route to IAA at 30 degrees C. The effects of growth temperature on auxin levels have been reported previously, but no prior studies correlated these effects with which pathway becomes the primary one for IAA production. 相似文献
100.
Molecular analysis of gene expression in the developing pontocerebellar projection system 总被引:7,自引:0,他引:7
Díaz E Ge Y Yang YH Loh KC Serafini TA Okazaki Y Hayashizaki Y Speed TP Ngai J Scheiffele P 《Neuron》2002,36(3):417-434
As an approach toward understanding the molecular mechanisms of neuronal differentiation, we utilized DNA microarrays to elucidate global patterns of gene expression during pontocerebellar development. Through this analysis, we identified groups of genes specific to neuronal precursor cells, associated with axon outgrowth, and regulated in response to contact with synaptic target cells. In the cerebellum, we identified a phase of granule cell differentiation that is independent of interactions with other cerebellar cell types. Analysis of pontine gene expression revealed that distinct programs of gene expression, correlated with axon outgrowth and synapse formation, can be decoupled and are likely influenced by different cells in the cerebellar target environment. Our approach provides insight into the genetic programs underlying the differentiation of specific cell types in the pontocerebellar projection system. 相似文献