Search results for "Triphosphatase"
showing 10 items of 89 documents
CtsR is the master regulator of stress response gene expression in Oenococcus oeni.
2005
ABSTRACT Although many stress response genes have been characterized in Oenococcus oeni , little is known about the regulation of stress response in this malolactic bacterium. The expression of eubacterial stress genes is controlled both positively and negatively at the transcriptional level. Overall, negative regulation of heat shock genes appears to be more widespread among gram-positive bacteria. We recently identified an ortholog of the ctsR gene in O. oeni . In Bacillus subtilis , CtsR negatively regulates expression of the clp genes, which belong to the class III family of heat shock genes. The ctsR gene of O. oeni is cotranscribed with the downstream clpC gene. Sequence analysis of t…
The nucleosome remodeling factor ISWI functionally interacts with an evolutionarily conserved network of cellular factors
2010
Abstract ISWI is an evolutionarily conserved ATP-dependent chromatin remodeling factor playing central roles in DNA replication, RNA transcription, and chromosome organization. The variety of biological functions dependent on ISWI suggests that its activity could be highly regulated. Our group has previously isolated and characterized new cellular activities that positively regulate ISWI in Drosophila melanogaster. To identify factors that antagonize ISWI activity we developed a novel in vivo eye-based assay to screen for genetic suppressors of ISWI. Our screen revealed that ISWI interacts with an evolutionarily conserved network of cellular and nuclear factors that escaped previous genetic…
Nuclear Translocation of Mismatch Repair Proteins MSH2 and MSH6 as a Response of Cells to Alkylating Agents
2000
Mammalian mismatch repair has been implicated in mismatch correction, the prevention of mutagenesis and cancer, and the induction of genotoxicity and apoptosis. Here, we show that treatment of cells specifically with agents inducing O(6)-methylguanine in DNA, such as N-methyl-N'-nitro-N-nitrosoguanidine and N-methyl-N-nitrosourea, elevates the level of MSH2 and MSH6 and increases GT mismatch binding activity in the nucleus. This inducible response occurs immediately after alkylation, is long-lasting and dose-dependent, and results from translocation of the preformed MutSalpha complex (composed of MSH2 and MSH6) from the cytoplasm into the nucleus. It is not caused by an increase in MSH2 gen…
Differential salinity-induced variations in the activity of H+-pumps and Na+/H+ antiporters that are involved in cytoplasm ion homeostasis as a funct…
2011
The characterisation of cellular responses to salinity in staple crops is necessary for the reliable identification of physiological markers of salinity tolerance. Under saline conditions, variations in proton gradients that are generated by membrane-bound H⁺ pumps are crucial for maintaining cytoplasm homeostasis. We examined short (15 h) and longer term effects (4 days) of NaCl stress on the H⁺ pumping activities that are associated with the plasma membrane (P-ATPase) and the tonoplast (V-ATPase and V-PPase) in rice (Oryza sativa L.) callus lines that displayed different levels of NaCl tolerance and were established from two japonica rice cultivars. The applied stress conditions were base…
Multiple roles for ISWI in transcription, chromosome organization and DNA replication.
2003
ISWI functions as the ATPase subunit of multiple chromatin-remodeling complexes. These complexes use the energy of ATP hydrolysis to slide nucleosomes and increase chromatin fluidity, thereby modulating the access of transcription factors and other regulatory proteins to DNA. Here we discuss recent progress toward understanding the biological functions of ISWI, with an emphasis on its roles in transcription, chromosome organization and DNA replication.
Binding and/or hydrolysis of purine‐based nucleotides is not required for IM30 ring formation
2021
IM30, the inner membrane-associated protein of 30 kDa, is conserved in cyanobacteria and chloroplasts. Although its exact physiological function is still mysterious, IM30 is clearly essential for thylakoid membrane biogenesis and/or dynamics. Recently, a cryptic IM30 GTPase activity has been reported, albeit thus far no physiological function has been attributed to this. Yet, it is still possible that GTP binding/hydrolysis affects formation of the prototypical large homo-oligomeric IM30 ring and rod structures. Here, we show that the Synechocystis sp. PCC 6803 IM30 protein in fact is an NTPase that hydrolyzes GTP and ATP, but not CTP or UTP, with about identical rates. While IM30 forms lar…
Eel ATPase activity as biomarker of thiobencarb exposure
2003
Abstract European eels ( Anguilla anguilla ) were exposed to a sublethal thiobencarb concentration of 0.22 mg/L in a flow-through system for 96 h. Mg 2+ and Na + –K + adenosine triphosphatase (ATPase) activities were evaluated in gill and muscle tissues at 2, 12, 24, 48, 72, and 96 h of thiobencarb exposure. Gill ATPase activities were rapidly inhibited from 2 h of contact onward. Highest inhibition was registered for Na + , K + -ATPase (85%) from 2 to 12 h. Both Mg 2+ and total ATPase were inhibited (>73%) during the first hours of toxicant exposure. At the end of the exposure period (96 h) ATPase activities were still different from those of the controls (>50%). Significant inhibition was…
Effects of primary- and secondary-treated bleached kraft mill effluents on the immune system and physiological parameters of roach.
2000
The present study was designed to examine, whether, effluents from a modern pulp and paper mill using elemental chlorine-free/total chlorine-free (ECF/TCF) bleaching, exert effects on the immune system of fish and, in addition, to relate these findings to physiological parameters known to be affected by bleached kraft-mill effluents (BKME). Roach (Rutilus rutilus) were exposed in laboratory conditions to primary- or secondary-treated effluent from a pulp and paper mill. In order to study their capability to respond to foreign antigens they were immunised with bovine gamma-globulin (BGG) prior to exposure. The number of anti-BGG antibody-secreting cells (ASC) and the number of immunoglobulin…
Hepatitis B virus maturation is sensitive to functional inhibition of ESCRT-III, Vps4, and gamma 2-adaptin.
2007
ABSTRACT Hepatitis B virus (HBV) is an enveloped DNA virus that presumably buds at intracellular membranes of infected cells. HBV budding involves two endocytic host proteins, the ubiquitin-interacting adaptor γ2-adaptin and the Nedd4 ubiquitin ligase. Here, we demonstrate that HBV release also requires the cellular machinery that generates internal vesicles of multivesicular bodies (MVBs). In order to perturb the MVB machinery in HBV-replicating liver cells, we used ectopic expression of dominant-negative mutants of different MVB components, like the ESCRT-III complex-forming CHMP proteins and the Vps4 ATPases. Upon coexpression of mutated CHMP3, CHMP4B, or CHMP4C forms, as well as of ATPa…
Morphology of experimentally denervated and reinnervated rat facial muscle I. Histochemical and histological findings
1994
The morphological changes in rat facial muscles were evaluated after permanent denervation and were compared with findings after immediate reinnervation. Thirty rats underwent transection of the left and right facial nerves immediately followed by hypoglossal-facial nerve anastomosis on the right side (muscular reinnervation) and removal of 8-10 mm of the facial plexus on the left side (permanent muscular denervation). Levator labii muscle samples of both sides were collected sequentially at 2, 6, 7, 10, 20, and 24 weeks after surgery and submitted to routine histological and enzyme histochemical staining procedures. In normal levator labii muscles a typical "chessboard" pattern was found, …