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71.
Charlène Cornilleau Noureddine Atmane Eric Jacquet Callum Smits Juan C. Alonso Paulo Tavares Leonor Oliveira 《Nucleic acids research》2013,41(1):340-354
The large terminase subunit is a central component of the genome packaging motor from tailed bacteriophages and herpes viruses. This two-domain enzyme has an N-terminal ATPase activity that fuels DNA translocation during packaging and a C-terminal nuclease activity required for initiation and termination of the packaging cycle. Here, we report that bacteriophage SPP1 large terminase (gp2) is a metal-dependent nuclease whose stability and activity are strongly and preferentially enhanced by Mn2+ ions. Mutation of conserved residues that coordinate Mn2+ ions in the nuclease catalytic site affect the metal-induced gp2 stabilization and impair both gp2-specific cleavage at the packaging initiation site pac and unspecific nuclease activity. Several of these mutations block also DNA encapsidation without affecting ATP hydrolysis or gp2 C-terminus binding to the procapsid portal vertex. The data are consistent with a mechanism in which the nuclease domain bound to the portal switches between nuclease activity and a coordinated action with the ATPase domain for DNA translocation. This switch of activities of the nuclease domain is critical to achieve the viral chromosome packaging cycle. 相似文献
72.
73.
Abdelhamid Khaldi Rebai Ben Ammar Su Young Woo Noureddine Akrimi Ezzeddine Zid 《Acta Physiologiae Plantarum》2011,33(3):765-775
The salinity tolerance and ion transport of 2-month-old seedlings of stone pine (Pinus pinea L.) grown in hydroponic solution containing various concentrations of NaCl (0–100 mM) were studied. The presence of salt
of up to 100 mM did not significantly reduce growth. Seedling hydration was insensitive to salinity. High salt concentrations
reduced K+ and Ca2+ uptake, root accumulation, and export to shoots. Na+ and Cl− ions, representing the major part of the ionic uptake, were effectively compartmentalized in vacuoles. We concluded that
seedlings of stone pine cultivated hydroponically were highly tolerant to salt concentrations of up to 100 mM for a culture
period of 38 days. This tolerance was associated with the accumulation of Na+ and Cl− ions in the shoots. 相似文献
74.
Jennifer Harris-Hellal Michel Grimaldi Evelyne Garnier-Zarli Noureddine Bousserrhine 《Biogeochemistry》2011,103(1-3):223-234
Iron oxy(hydr)oxides (oxides) are important mercury sinks in tropical oxisols and the geochemistry of these two elements are thus closely entwined. We hypothesized that bacterial Fe-oxide reduction in anoxic conditions could be a significant mechanism for mobilizing associated Hg. Iron oxide and mercury solubilisation in presence of two chemical reducers (ascorbate and dithionite, dissolving amorphous and amorphous plus well crystallized Fe-oxides, respectively) was compared to their solubilisation in presence of autochthonous ferri-reducing bacteria. This work was carried out on two soil profiles from a small catchment basin in French Guyana, an oxisol (O) from a well drained slope and a water-saturated hydromorphic soil (H). The chemical reductions showed that in the oxisol 20 and 48% of total Hg (HgT) was associated to amorphous and well crystallized iron oxides, respectively. However, in the hydromorphic soil, no Hg seemed to be associated to amorphous iron oxides while the well crystallized fraction contained less than 9% of HgT. Chemical Fe-oxide reduction showed that Hg solubility was correlated to Fe reduction in the oxisol, demonstrating a relationship between the geochemistry of these two metals. During bacterial growth, while bacterial iron reduction solubilised up to 3.2 mg Fe g?1 soil in the oxisol sample, HgT remained unchanged. No mercury was detected in the culture medium either. However, chemical analysis showed a decrease of the amounts of Hg associated to amorphous and well crystallized Fe-oxides after 14 days of incubation, underlining the potential for iron-reducing bacteria to modify mercury distribution in soil. 相似文献
75.
Bechr Hamrita Hela Ben Nasr Sallouha Gabbouj Noureddine Bouaouina Lotfi Chouchane Karim Chahed 《Molecular biology reports》2011,38(3):1637-1643
Apolipoprotein A1 (ApoA1) is the major apoprotein constituent of high-density lipoprotein that can play important roles in
tumor invasion and metastasis. In the current report, we evaluated the role of the functional ApoA1 polymorphisms (−75 G/A
and +83 C/T) as genetic markers for breast cancer susceptibility and prognosis. We used the polymerase chain reaction and
restriction enzyme digestion (RFLP-PCR) to characterize the variations of the ApoA1 gene in 295 unrelated Tunisian patients
with breast carcinoma and 197 healthy control subjects. No association was found between the +83 C/T genetic variation in
ApoA1 gene and the risk of breast cancer occurrence. The presence of the (+83) T allele appeared however to be associated
with an increased risk of lymph node metastasis occurrence (OR = 2.94; P = 0.01). Furthermore, a positive association was found between ApoA1 −75 A allele carriers and breast cancer risk (OR = 1.57;
P = 0.02). Regarding prognostic indicators, a significant association was found between ApoA1 (−75) A allele carriers and the
premenopausal status of breast cancer patients (OR = 1.73; P = 0.03). Additionally, the presence of the −75 A allele was correlated with the oestrogen receptor status among premenopausal
women (OR = 2.45; P = 0.02). This is the first report on the studies of ApoA1 single nucleotide polymorphisms (SNPs) in breast carcinomas. Our
data suggest that these genetic variations of ApoA1 may represent a marker for the increased risk of breast cancer. 相似文献
76.
Birukova AA Zebda N Cokic I Fu P Wu T Dubrovskyi O Birukov KG 《Experimental cell research》2011,(6):859-872
Products resulting from oxidation of cell membrane phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC) exhibit potent protective effects against lung endothelial cell (EC) barrier dysfunction caused by pathologically relevant mechanical forces and inflammatory agents. These effects were linked to enhancement of peripheral cytoskeleton and cell adhesion interactions mediated by small GTPase Rac and inhibition of Rho-mediated barrier-disruptive signaling. However, the mechanism of OxPAPC-induced, Rac-dependent Rho downregulation critical for vascular barrier protection remains unclear. This study tested the hypothesis that Rho negative regulator p190RhoGAP is essential for OxPAPC-induced lung barrier protection against ventilator-induced lung injury (VILI), and investigated potential mechanism of p190RhoGAP targeting to adherens junctions (AJ) via p120-catenin. OxPAPC induced peripheral translocation of p190RhoGAP, which was abolished by knockdown of Rac-specific guanine nucleotide exchange factors Tiam1 and Vav2. OxPAPC also induced Rac-dependent tyrosine phosphorylation and association of p190RhoGAP with AJ protein p120-catenin. siRNA-induced knockdown of p190RhoGAP attenuated protective effects of OxPAPC against EC barrier compromise induced by thrombin and pathologically relevant cyclic stretch (18% CS). In vivo, p190RhoGAP knockdown significantly attenuated protective effects of OxPAPC against ventilator-induced lung vascular leak, as detected by increased cell count and protein content in the bronchoalveolar lavage fluid, and tissue neutrophil accumulation in the lung. These results demonstrate for the first time a key role of p190RhoGAP for the vascular endothelial barrier protection in VILI. 相似文献
77.
Lazar N Brakch N Panchal M Fahy C Rholam M 《Archives of biochemistry and biophysics》2007,463(2):231-236
Statistical analysis of several potential dibasic cleavage sites reveals differences in the distribution of basic doublets when the in vivo cleaved sites were compared to those which are not cleaved. Analysis of the substrate specificity of protease Kex2 towards the pro-ocytocin/neurophysin processing domain (pro-OT/Np(7-15) with altered basic pairs shows a cleavage efficiency order in accord with the statistical data. Structural analysis of these substrates indicates that each basic pair is associated with a local and specific conformational change. Thus, the in vivo cleavage hierarchy of dibasic sites is encoded by both the nature of basic pairs and the plasticity of proteolytic processing domains. 相似文献
78.
Saddoud O Chatti K Salhi-Hannachi A Mars M Rhouma A Marrakchi M Trifi M 《Hereditas》2007,144(4):149-157
The present study portrays the achievement of the genetic polymorphism surveying and the establishment of an ecotypes identification key on the basis of simple sequence repeats data. Seventy-two Tunisian fig ecotypes in situ and ex situ conserved were analyzed using six microsatellite loci. A total of 58 alleles and 124 genotypes were revealed and permitted to evidence high degree of genetic diversity mainly explained at the intra group level. Cluster analysis based on genetic distances proved that a typical continuous genetic diversity characterizes the local germplasm. In addition, the microsatellite multilocus genotyping has permitted to unambiguously distinguish 70 well-defined ecotypes (resolving power of 97.22%). Data are discussed in relation with the reliability of the used markers to check the conformity of the plant material and to rationally manage the conservation of this crop. 相似文献
79.
80.
Barrachina I Royo I Baldoni HA Chahboune N Suvire F DePedro N Zafra-Polo MC Bermejo A El Aouad N Cabedo N Saez J Tormo JR Enriz RD Cortes D 《Bioorganic & medicinal chemistry》2007,15(13):4369-4381
We describe herein the isolation and semisynthesis of four acetogenin derivatives (1-4) as well as their ability to inhibit the mitochondrial respiratory chain and several tumor cell lines. In addition, four nanoseconds (ns) of MD simulation of compound 4, in a fully hydrated POPC bilayer, is reported. 相似文献