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61.
A novel family of sequence-specific endoribonucleases associated with the clustered regularly interspaced short palindromic repeats 总被引:3,自引:0,他引:3
Beloglazova N Brown G Zimmerman MD Proudfoot M Makarova KS Kudritska M Kochinyan S Wang S Chruszcz M Minor W Koonin EV Edwards AM Savchenko A Yakunin AF 《The Journal of biological chemistry》2008,283(29):20361-20371
Clustered regularly interspaced short palindromic repeats (CRISPRs) together with the associated CAS proteins protect microbial cells from invasion by foreign genetic elements using presently unknown molecular mechanisms. All CRISPR systems contain proteins of the CAS2 family, suggesting that these uncharacterized proteins play a central role in this process. Here we show that the CAS2 proteins represent a novel family of endoribonucleases. Six purified CAS2 proteins from diverse organisms cleaved single-stranded RNAs preferentially within U-rich regions. A representative CAS2 enzyme, SSO1404 from Sulfolobus solfataricus, cleaved the phosphodiester linkage on the 3'-side and generated 5'-phosphate- and 3'-hydroxyl-terminated oligonucleotides. The crystal structure of SSO1404 was solved at 1.6A resolution revealing the first ribonuclease with a ferredoxin-like fold. Mutagenesis of SSO1404 identified six residues (Tyr-9, Asp-10, Arg-17, Arg-19, Arg-31, and Phe-37) that are important for enzymatic activity and suggested that Asp-10 might be the principal catalytic residue. Thus, CAS2 proteins are sequence-specific endoribonucleases, and we propose that their role in the CRISPR-mediated anti-phage defense might involve degradation of phage or cellular mRNAs. 相似文献
62.
Krendeleva T. E. Kukarskikh G. P. Makarova V. V. Lavrukhina O. G. Nizovskaya N. V. 《Russian Journal of Plant Physiology》2001,48(3):340-344
The rates of electron transfer in the presence of natural cofactors, ferredoxin and NADP, which were added in the amounts catalyzing noncyclic or cyclic electron transfer, were studied in thylakoids isolated from 17-day-old wheat seedlings. Upon excitation of both photosystems (PS) of photosynthesis, the potential rate of NADP reduction in thylakoids isolated from plants grown on nitrogen-free nutrient solution did not differ from that in thylakoids from the control plants. However, the P/2e ratio was significantly lower in thylakoids isolated from nitrogen-deficient plants. On the contrary, in the presence of DCMU, the rate of PSI-driven electron transfer from an artificial donor to NADP was considerably higher in these than in the control thylakoids. In the presence of ferredoxin under anaerobic conditions, the rate of phosphorylation coupled to cyclic electron transport was also significantly higher in thylakoids isolated from nitrogen-deficient plants, than in thylakoids isolated from control plants. Our data show that PSI-driven electron transport and cyclic photophosphorylation are activated in nitrogen-starved wheat plants, at least at the initial stages of starvation. 相似文献
63.
T M Makarova E I Varlinskaia T I Chasovnikova E S Petrov 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1991,41(6):1231-1238
It is shown, that rats, bred in conditions of intraspecies isolation are able to competition for water in the kin group, having usual experience of intraspecies intercourse. At the same level of drinking motivation in conditions of competition for water the intraspecies activity is significantly higher in rats, bred in isolation in comparison with grouped animals. Rats-isolants significantly more often than the grouped animals use extraordinary tactics of intraspecies behaviour, which increase their competitive ability in conditions of limited access to water. 相似文献
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V A Makarova 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1978,(4):112-116
The authors present data concerning the study of the antigenic properties of rickettisa of the tick-borne spotted fever group isolated from the Ixodes ticks in the Armenain SSR. In order to determine the species of the isolated strains a method of serological identification of rickettsia in the complement fixation reaction with the species-specific immune sera of albino mice was used. The results obtained permitted to refer the Armenia-74, No. 11, 29, and 57 species to the R. sibricia species. 相似文献
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Olga Makarova Alex Rodriguez-Rojas Murat Eravci Chris Weise Adam Dobson Paul Johnston Jens Rolff 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2016,371(1695)
Insects show long-lasting antimicrobial immune responses that follow the initial fast-acting cellular processes. These immune responses are discussed to provide a form of phrophylaxis and/or to serve as a safety measure against persisting infections. The duration and components of such long-lasting responses have rarely been studied in detail, a necessary prerequisite to understand their adaptive value. Here, we present a 21 day proteomic time course of the mealworm beetle Tenebrio molitor immune-challenged with heat-killed Staphylococcus aureus. The most upregulated peptides are antimicrobial peptides (AMPs), many of which are still highly abundant 21 days after infection. The identified AMPs included toll and imd-mediated AMPs, a significant number of which have no known function against S. aureus or other Gram-positive bacteria. The proteome reflects the selective arena for bacterial infections. The results also corroborate the notion of synergistic interactions in vivo that are difficult to model in vitro.This article is part of the themed issue ‘Evolutionary ecology of arthropod antimicrobial peptides’. 相似文献
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A steady-state model of spreading depression predicts the importance of an unknown conductance in specific dendritic domains 下载免费PDF全文
Spreading depression (SD) is a pathological wave of transient neuronal inactivation. We recently reported that the characteristic sustained complete depolarization is restricted to specific cell domains where the input resistance (R(in)) first becomes negligible before achieving partial recovery, whereas in adjacent, more polarized membranes it drops by much less. The experimental study of the participating membrane channels is hindered by their mixed contribution and heterogeneous distribution. Therefore, we derived a biophysical model to analyze the conductances that replicate the subcellular profile of R(in) during SD. Systematic variation of conductance densities far beyond the ranges reported failed to fit the experimental values. Besides standard potassium, sodium, and Glu-mediated conductances, the initial opening and gradual closing of an as yet undetermined large conductance is required to account for the evolution of R(in). Potassium conductances follow in the relative contribution and their closing during the late phase is also predicted. Large intracellular potential gradients from zero to rest are readily sustained between shunted and adjacent SD-spared membranes, which remain electroregenerative. The gradients are achieved by a combination of high-conductance subcellular domains and transmembrane ion redistribution in extended but discrete dendritic domains. We conclude that the heterogeneous subcellular behavior is due to local membrane properties, some of which may be specifically activated under extreme SD conditions. 相似文献