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101.
Loading of Arabidopsis centromeric histone CENH3 occurs mainly during G2 and requires the presence of the histone fold domain
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The centromeric histone H3 (CENH3) substitutes histone H3 within the nucleosomes of active centromeres in all eukaryotes. CENH3 deposition at centromeres is needed to assemble the kinetochore, a complex of conserved proteins responsible for correct chromosome segregation during nuclear division. Histones of regular nucleosomes are loaded during replication in S phase, while CENH3 deposition deviates from this pattern in yeast, human, and Drosophila melanogaster cells. Little is known about when and how CENH3 targets centromeric loci. Therefore, we determined the location and quantity of recombinant enhanced yellow fluorescent protein (EYFP)-CENH3 in mitotic root and endopolyploid leaf nuclei of transgenic Arabidopsis thaliana cells. Our data indicate significant loading of A. thaliana CENH3 during G2 (before splitting into sister kinetochores) rather than during the S or M phase of the cell cycle. The histone fold domain of the C-terminal part of CENH3 is sufficient to target A. thaliana centromeres. A. thaliana EYFP-CENH3 can recognize and target three different centromeric repeats of Arabidopsis lyrata but not field bean (Vicia faba) centromeres. 相似文献
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103.
Everberg H Peterson R Rak S Tjerneld F Emanuelsson C 《Journal of proteome research》2006,5(5):1168-1175
For proteomic monitoring of processes such as allergy or inflammation an efficient pre-fractionation strategy is required. We isolated plasma membranes from human peripheral blood mononuclear (PBM) cells by aqueous two-phase partitioning. After 1DE combined with LC-MS/MS, several cell surface marker proteins and in total 60 different plasma membrane proteins (out of 84 identified proteins, i.e., 72%) were detected. Plasma membranes obtained were from only one human donor, the procedure is therefore applicable for individual patient screening. 相似文献
104.
Maria Nagy Izabela Guenther Micheal E. Barnett Sabina Kedzierska-Mieszkowska 《Journal of molecular biology》2010,396(3):697-707
Bacterial AAA+ ATPase ClpB cooperates with DnaK during reactivation of aggregated proteins. The ClpB-mediated disaggregation is linked to translocation of polypeptides through the channel in the oligomeric ClpB. Two isoforms of ClpB are produced in vivo: the full-length ClpB95 and ClpB80, which does not contain the substrate-interacting N-terminal domain. The biological role of the truncated isoform ClpB80 is unknown. We found that resolubilization of aggregated proteins in Escherichia coli after heat shock and reactivation of aggregated proteins in vitro and in vivo occurred at higher rates in the presence of ClpB95 with ClpB80 than with ClpB95 or ClpB80 alone. Combined amounts of ClpB95 and ClpB80 bound to aggregated substrates were similar to the amounts of either ClpB95 or ClpB80 bound to the substrates in the absence of another isoform. The ATP hydrolysis rate of ClpB95 with ClpB80, which is linked to the rate of substrate translocation, was not higher than the rates measured for the isolated ClpB95 or ClpB80. We postulate that a reaction step that takes place after substrate binding to ClpB and precedes substrate translocation is rate-limiting during aggregate reactivation, and its efficiency is enhanced in the presence of both ClpB isoforms. Moreover, we found that ClpB95 and ClpB80 form hetero-oligomers, which are similar in size to the homo-oligomers of ClpB95 or ClpB80. Thus, the mechanism of functional cooperation of the two isoforms of ClpB may be linked to their heteroassociation. Our results suggest that the functionality of other AAA+ ATPases may be also optimized by interaction and synergistic cooperation of their isoforms. 相似文献
105.
106.
Vagnerova I Sauer P Kolar M Slepickova S Hubacek J Faber E Raida L Papajik T 《Biomedical papers of the Medical Faculty of the University Palacky, Olomouc, Czechoslovakia》2006,150(1):117-120
The presented study aims at analyzing an increasing prevalence of vancomycin-resistant enterococci (VRE) isolated from various kinds of clinical material obtained from patients in the Department of Hemato-oncology (DHO), University Hospital in Olomouc, Czech Republic. Between January 1 and March 31, 2005, enterococci were isolated by standard microbiological procedures using both clinical material obtained from hospitalized patients and samples from the department environment. Resistance to vancomycin and teicoplanin was determined by a standardized microdilution method. Phenotype determination of resistance to vancomycin was verified by PCR detection of vanA and vanB genes. In VanA Enterococcus faecium, macrorestriction analysis was performed by pulsed-field gel electrophoresis. During the monitored period, a total of 128 Enterococcus sp. strains were isolated, of which 38 (30 %) isolates from 22 different patients were determined as VRE. Dominating were Enterococcus faecium VanA (63 %) and Enterococcus casseliflavus VanC (16 %) strains. At the same time, one Enterococcus faecium VanA strain was acquired from a bed-side table used by a patient in whom a similar strain had been isolated repeatedly from various clinical materials including a rectal swab taken in 2004. Based on the macrorestriction analysis of genome DNA in 24 vancomycin-resistant Enterococcus faecium VanA strains isolated from the patients' clinical material, one strain from the bed-side table surface and one strain isolated from stools in 2004, 8 unique restriction profiles with similarity ranging from 90 % to 100 % were identified, which could be classified into 3 clonal types. Thus, we can assume not only the endogenous origin of the VRE in hemato-oncological patients and their potential selection caused by therapy with broad-spectrum antibiotics but also the ability of the strains to survive in a hospital setting and, subsequently, to be spread clonally by various vectors. 相似文献
107.
108.
Analyzing peroxisomal phosphoinositide (PId(#)) synthesis in highly purified rat liver peroxisomes we found synthesis of phosphatidylinositol 4-phosphate (PtdIns4P), PtdIns(4,5)P(2) and PtdIns(3,5)P(2). PtdIns3P was hardly detected in vitro, however, was observed in vivo after [(32)P]-phosphate labeling of primary rat hepatocytes. In comparison with other subcellular organelles peroxisomes revealed a unique PId pattern suggesting peroxisomal specificity of the observed synthesis. Use of phosphatase inhibitors enhanced the amount of PtdIns4P. The results obtained provide evidence that isolated rat liver peroxisomes synthesize PIds and suggest the association of PId 4-kinase and PId 5-kinase and PId 4-phosphatase activities with the peroxisomal membrane. 相似文献
109.
Pavlovic M Schaller A Ammann RA Sanz J Pfammatter JP Carrel T Berdat P Gallati S 《Biochemical and biophysical research communications》2006,342(1):310-315
Myocardial dysfunction and arrhythmias may be induced by congenital heart defects, but also be the result of heart surgery with cardiopulmonary bypass (CPB), potentially caused by differential expression of connexin40 (Cx40) and connexin43 (Cx43). In 16 pediatric patients undergoing corrective heart surgery, connexin mRNA expression was studied in volume overloaded (VO group, n=8) and not overloaded (NO group, n=8) right atrial myocardium, excised before and after CPB. Additionally, in eight of these patients ventricular specimens were investigated. The atrial Cx43 expression decreased during CPB, which was restricted to the VO group (p=0.008). In contrast, atrial Cx40 mRNA did not change during CPB. In ventricular myocardium compared to atrial mRNA levels, Cx40 was lower (p=0.006) and Cx43 higher (p=0.017) expressed, without significant change during CPB. This study revealed a significant influence of CPB and the underlying heart defect on Cx43 expression. 相似文献
110.
The interaction of T0lymphocytes with antigen-presenting cells displaying a small number of specific peptide/major histocompatibility
complexes results in the downregulation of a large number of T-cell receptors (TCR), suggesting serial TCR triggering. However,
the details of TCR downregulation are controversial. In particular, the level of comodulation of nonengaged TCR reported by
different authors ranges from essentially none to considerable levels. Here, we address this controversy using complementary
experimental and mathematical techniques. We find that TCR downregulation is very rapid during the first 2–4 min after T-cell
antigen-presenting cells contact formation. After this phase, TCR downregulation proceeds at a relatively slow rate. Statistical
and computational analyses show that this pronounced change in downregulation kinetics is compatible with the notion of initial
serial triggering of clustered TCR followed by serial triggering of individual TCR. We further propose a compatible mechanism
for concurrent triggering of multiple TCR by a single peptide/major histocompatibility complex. We provide a unified picture
of productive TCR engagement and downregulation in which TCR triggering characteristics evolve from an initial cooperative
phase to a sustained phase of signal accumulation. 相似文献