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21.
Ekaterina Y. Bezsudnova Konstantin M. Boyko Konstantin M. Polyakov Pavel V. Dorovatovskiy Tatiana N. Stekhanova Vadim M. Gumerov Nikolai V. Ravin Konstantin G. Skryabin Michael V. Kovalchuk Vladimir O. Popov 《Biochimie》2012
Biochemical analysis of enantioselective short-chain alcohol dehydrogenase from the hyperthermophilic archaeon Thermococcus sibiricus (TsAdh319) revealed unique polyextremophilic properties of the enzyme – half-life of 1 h at 100 °C, tolerance to high salt (up to 4 M) and organic solvents (50% v/v) concentrations. To elucidate the molecular basis of TsAdh319 polyextremophilicity, we determined the crystal structure of the enzyme in a binary complex with 5-hydroxy-NADP at 1.68 Å resolution. TsAdh319 has a tetrameric structure both in the crystals and in solution with an intersubunit disulfide bond. The substrate-binding pocket is hydrophobic, spacious and open that is consistent with the observed promiscuity in substrate specificity of TsAdh319. The present study revealed an extraordinary number of charged residues on the surface of TsAdh319, 70% of which were involved in ion pair interactions. Further we compared the structure of TsAdh319 with the structures of other homologous short-chain dehydrogenases/reductases (SDRs) from thermophilic and mesophilic organisms. We found that TsAdh319 has the highest arginine and aspartate + glutamate contents compared to the counterparts. The frequency of occurrence of salt bridges on the surface of TsAdh319 is the highest among the SDRs under consideration. No differences in the proline, tryptophan, and phenylalanine contents are observed; the compactness of the protein core of TsAdh319, the monomer and tetramer organization do not differ from that of the counterparts. We suggest that the unique thermostability of TsAdh319 is associated with the rigidity and simultaneous “resilience” of the structure provided by a compact hydrophobic core and a large number of surface ion pairs. An extensive salt bridge network also might maintain the structural integrity of TsAdh319 in high salinity. 相似文献
22.
Francisco Zamorano Pablo Billeke José M. Hurtado Vladimir López Ximena Carrasco Tomás Ossandón Francisco Aboitiz 《PloS one》2014,9(1)
The capacity to inhibit prepotent and automatic responses is crucial for proper cognitive and social development, and inhibitory impairments have been considered to be key for some neuropsychiatric conditions. One of the most used paradigms to analyze inhibitory processes is the Go-Nogo task (GNG). This task has been widely used in psychophysical and cognitive EEG studies, and more recently in paradigms using fMRI. However, a technical limitation is that the time resolution of fMRI is poorer than that of the EEG technique. In order to compensate for these temporal constraints, it has become common practice in the fMRI field to use longer inter-stimulus intervals (ISI) than those used in EEG protocols. Despite the noticeable temporal differences between these two techniques, it is currently assumed that both approaches assess similar inhibitory processes. We performed an EEG study using a GNG task with both short ISI (fast-condition, FC, as in EEG protocols) and long ISI (slow-condition, SC, as in fMRI protocols). We found that in the FC there was a stronger Nogo-N2 effect than in the SC. Moreover, in the FC, but not in the SC, the number of preceding Go trials correlated positively with the Nogo-P3 amplitude and with the Go trial reaction time; and negatively with commission errors. In addition, we found significant topographical differences for the Go-P3 elicited in FC and SC, which is interpreted in terms of different neurotransmitter dynamics. Taken together, our results provide evidence that frequency of stimulus presentation in the GNG task strongly modulates the behavioral response and the evoked EEG activity. Therefore, it is likely that short-ISI EEG protocols and long-ISI fMRI protocols do not assess equivalent inhibitory processes. 相似文献
23.
Pascal Vallotton Antoine M. van Oijen Cynthia B. Whitchurch Vladimir Gelfand Leslie Yeo Georgios Tsiavaliaris Stephanie Heinrich Elisa Dultz Karsten Weis David Grünwald 《Traffic (Copenhagen, Denmark)》2017,18(12):840-852
Object tracking is an instrumental tool supporting studies of cellular trafficking. There are three challenges in object tracking: the identification of targets; the precise determination of their position and boundaries; and the assembly of correct trajectories. This last challenge is particularly relevant when dealing with densely populated images with low signal‐to‐noise ratios—conditions that are often encountered in applications such as organelle tracking, virus particle tracking or single‐molecule imaging. We have developed a set of methods that can handle a wide variety of signal complexities. They are compiled into a free software package called Diatrack. Here we review its main features and utility in a range of applications, providing a survey of the dynamic imaging field together with recommendations for effective use. The performance of our framework is shown to compare favorably to a wide selection of custom‐developed algorithms, whether in terms of localization precision, processing speed or correctness of tracks. 相似文献
24.
The potassium salt-induced transient increase of delayed fluorescence yield was studied in pea chloroplasts treated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea.A simple kinetic model is proposed to account for the actinic light intensity dependence of the delayed fluorescence enhancement by the transmembrane diffusion potential induced by sudden salt addition. The electric field dependence of the rate constants for the recombination of primary separated charges with and without subsequent electronic excitation of reaction center chlorophyll was obtained.From the value of enhancement of delayed fluorescence by salt concentration gradients at saturating actinic light intensity, it is concluded that the distance, normal to thylakoid membrane surface, between the primary acceptor and the donor of Photosystem II is smaller than the membrane thickness. 相似文献
25.
Vladimir E. Belozerov Srdjana Ratkovic Helen McNeill Arthur J. Hilliker John C. McDermott 《Molecular and cellular biology》2014,34(3):474-484
Several recent studies suggest that systemic aging in metazoans is differentially affected by functional decline in specific tissues, such as skeletal muscle. In Drosophila, longevity appears to be tightly linked to myoproteostasis, and the formation of misfolded protein aggregates is a hallmark of senescence in aging muscle. Similarly, defective myoproteostasis is described as an important contributor to the pathology of several age-related degenerative muscle diseases in humans, e.g., inclusion body myositis. p38 mitogen-activated protein kinase (MAPK) plays a central role in a conserved signaling pathway activated by a variety of stressful stimuli. Aging p38 MAPK mutant flies display accelerated motor function decline, concomitant with an enhanced accumulation of detergent-insoluble protein aggregates in thoracic muscles. Chemical genetic experiments suggest that p38-mediated regulation of myoproteostasis is not limited to the control of reactive oxygen species production or the protein degradation pathways but also involves upstream turnover pathways, e.g., translation. Using affinity purification and mass spectrometry, we identified Rack1 as a novel substrate of p38 MAPK in aging muscle and showed that the genetic interaction between p38b and Rack1 controls muscle aggregate formation, locomotor function, and longevity. Biochemical analyses of Rack1 in aging and stressed muscle suggest a model whereby p38 MAPK signaling causes a redistribution of Rack1 between a ribosome-bound pool and a putative translational repressor complex. 相似文献
26.
Oksana I. Dukhanina Vladimir E. Sverdlov Barbara Hoebee John P. Rapp 《Mammalian genome》1999,10(1):26-29
An improved linkage map for rat Chromosome (Chr) 10 with two F2 populations was constructed. Thirty new microsatellite markers were generated from a Chr 10-specific, small-insert genomic
library and mapped to rat Chr 10. Among them were the rat homologs for the mouse gene for light and heavy chains of myeloperoxidase
and human neurofibromatosis 1. Eight newly generated markers (D10Mco62, D10Mco63, D10Mco64, D10Mco65, D10Mco67, D10Mco68, D10Mco70, and D10Mco74) were mapped to the region of the rat Chr 10 blood pressure QTL. The availability of such markers may be instrumental in
the search for genes responsible for the hypertension.
Received: 13 July 1998 / Accepted: 9 September 1998 相似文献
27.
Kreslavski V Tatarinzev N Shabnova N Semenova G Kosobryukhov A 《Journal of plant physiology》2008,165(15):1592-1600
The nature of photosynthetic recovery was investigated in 10-d-old wheat (Triticum aestivum L., cv. Moskovskaya-35) seedlings exposed to temperatures of 40 and 42 °C for 20 min and to temperature 42 °C for 40 min in the dark. The aftereffect of heat treatment was monitored by growing the heat-treated plants in low/moderate/high light at 20 °C for 72 h. The net photosynthetic rates (PN) and the fluorescence ratios Fv/Fm were evaluated in intact primary leaves and the rates of cyclic and non-cyclic photophosphorylation were measured in the isolated thylakoids. At least two temporally separated steps were identified in the path of recovery from heat stress at 40 and 42 °C in the plants growing in high and moderate/high light, respectively. Both photochemical activity of the photosystem II (PSII) and the activity of CO2 assimilation system were lowered during the first step in comparison with the corresponding activities immediately after heat treatment. During the second step, the photosynthetic activities completely or partly recovered. Recovery from heat stress at 40 °C was accompanied by an appreciably higher rate of cyclic photophosphorylation in comparison with control non-heated seedlings. In pre-heated seedlings, the tolerance of the PSII to photoinhibition was higher than in non-treated ones. The mode of acclimation to different light intensities after heat exposures is analyzed. 相似文献
28.
Manoj Kumar Vladimir León Angela De Sisto Materano Olaf A. Ilzins 《World journal of microbiology & biotechnology》2007,23(2):211-220
A Bacillus sp. strain DHT, isolated from oil-contaminated soil, grew and produced biosurfactant when cultured in variety of substrate
at salinities of up to 100 g l−1 and temperatures up to 45°C. It was capable of utilizing crude oil, fuels, various pure alkanes and PAHs as a sole carbon
and energy source across a wide range of temperature and salinity. Over the range evaluated, the degradation of hydrocarbon
and biosurfactant production was not influenced by salinity (0–10% wv−1) and temperature (30–45°C). The biosurfactant produced by the organism emulsified a range of hydrocarbons with hexadecane
as the best substrate and toluene as the poorest. From 16S rDNA analysis, strain DHT was related to Bacillus licheniformis. 相似文献
29.
30.
Henriette L. Pedersen Jonatan U. Fangel Barry McCleary Christian Ruzanski Maja G. Rydahl Marie-Christine Ralet Vladimir Farkas Laura von Schantz Susan E. Marcus Mathias C. F. Andersen Rob Field Mats Ohlin J. Paul Knox Mads H. Clausen William G. T. Willats 《The Journal of biological chemistry》2012,287(47):39429-39438
Microarrays are powerful tools for high throughput analysis, and hundreds or thousands of molecular interactions can be assessed simultaneously using very small amounts of analytes. Nucleotide microarrays are well established in plant research, but carbohydrate microarrays are much less established, and one reason for this is a lack of suitable glycans with which to populate arrays. Polysaccharide microarrays are relatively easy to produce because of the ease of immobilizing large polymers noncovalently onto a variety of microarray surfaces, but they lack analytical resolution because polysaccharides often contain multiple distinct carbohydrate substructures. Microarrays of defined oligosaccharides potentially overcome this problem but are harder to produce because oligosaccharides usually require coupling prior to immobilization. We have assembled a library of well characterized plant oligosaccharides produced either by partial hydrolysis from polysaccharides or by de novo chemical synthesis. Once coupled to protein, these neoglycoconjugates are versatile reagents that can be printed as microarrays onto a variety of slide types and membranes. We show that these microarrays are suitable for the high throughput characterization of the recognition capabilities of monoclonal antibodies, carbohydrate-binding modules, and other oligosaccharide-binding proteins of biological significance and also that they have potential for the characterization of carbohydrate-active enzymes. 相似文献