Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The yeast SNF-SWI complex is required for transcriptional activation of diverse genes and has been shown to alter chromatin structure. The complex has at least 10 components, including SNF2/SWI2, SNF5, SNF6, SWI1/ADR6, and SWI3, and has been widely conserved in eukaryotes. Here we report the characterization of a new component. We identified proteins that interact in the two-hybrid system with the N-terminal region of SNF2, preceding the ATPase domain. In addition to SWI3, we recovered a new 19-kDa protein, designated SNF11. Like other SNF/SWI proteins, SNF11 functions as a transcriptional activator in genetic assays. SNF11 interacts with SNF2 in vitro and copurifies with the SNF-SWI complex from yeast cells. Using a specific antibody, we showed that SNF11 coimmunoprecipitates with members of the SNF-SWI complex and that SNF11 is tightly and stoichiometrically associated with the complex. Furthermore, SNF11 was detected in purified SNF-SWI complex by staining with Coomassie blue dye; its presence previously went unrecognized because it does not stain with silver. SNF11 interacts with a 40-residue sequence of SNF2 that is highly conserved, suggesting that SNF11 homologs exist in other organisms.
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PMID:SNF11, a new component of the yeast SNF-SWI complex that interacts with a conserved region of SNF2. 762 18

Replication of bovine papillomavirus type 1 (BPV-1) DNA has been shown to require two viral proteins known to interact in a molecular complex: E2, a transcription activator, and E1, another nuclear phosphoprotein, which binds to the replication origin and for which helicase/ATPase activities have previously been reported. Here we characterize the BPV-1 E1 ATPase activity. In contrast to Seo et al. (Proceedings of the National Academy of Sciences, USA, 90, 702-706, 1993), we were able to detect this activity in the absence of nucleic acid in partially purified preparations of either E1 protein or of E1-E2 protein complex. Measurements of specific activity and kinetic parameters gave similar values for preparations of various kinds. ATPase activity was quantitatively retained by immunoprecipitates obtained by using anti-E1 or, in the case of E1-E2 complex, anti-E2 antibodies. Significantly, preparations of bacterially expressed glutathione S-transferase-E1 fusion protein exhibited levels of DNA-independent ATPase activity comparable to those of baculovirus-expressed E1. The presence of nucleic acids of various types, including stoichiometric amounts of a BPV-1 ori DNA fragment containing E1 and E2 binding sites, did not grossly affect E1 ATPase activity, the most notable effect being a 2-fold stimulation by unspecific ssDNA. Altogether, our results indicate that BPV-1 E1 possesses an intrinsic ATPase activity which does not depend on the presence of nucleic acid; moreover, they render unlikely any modulation of E1 ATPase activity due to binding either E2 protein or target DNA sequences, or as a result of protein phosphorylation.
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PMID:Bovine papillomavirus type 1 E1 ATPase activity does not depend on binding to DNA nor to viral E2 protein. 773 Jul 98

The yeast SNF/SWI proteins have a global role in transcriptional activation. This set of five proteins assists many gene-specific activators, most likely by altering chromatin structure to relieve repression. Recent work shows that the SNF/SWI proteins function together in a multiprotein complex and that SNF2 has DNA-dependent ATPase activity. SNF/SWI homologs have now been identified in Drosophila, mice and humans, suggesting a conserved role in transcriptional activation.
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PMID:The SNF/SWI family of global transcriptional activators. 791 31

The SWI/SNF protein complex is required for the enhancement of transcription by many transcriptional activators in yeast. Here it is shown that the purified SWI/SNF complex is composed of 10 subunits and includes the SWI1, SWI2/SNF2, SWI3, SNF5, and SNF6 gene products. The complex exhibited DNA-stimulated adenosine triphosphatase (ATPase) activity, but lacked helicase activity. The SWI/SNF complex caused a 10- to 30-fold stimulation in the binding of GAL4 derivatives to nucleosomal DNA in a reaction that required adenosine triphosphate (ATP) hydrolysis but was activation domain-independent. Stimulation of GAL4 binding by the complex was abolished by a mutant SWI2 subunit, and was increased by the presence of a histone-binding protein, nucleoplasmin. A direct ATP-dependent interaction between the SWI/SNF complex and nucleosomal DNA was detected. These observations suggest that a primary role of the SWI/SNF complex is to promote activator binding to nucleosomal DNA.
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PMID:Stimulation of GAL4 derivative binding to nucleosomal DNA by the yeast SWI/SNF complex. 801 55

Sequence-specific DNA binding activators of gene transcription may be assisted by SWI2 (SNF2), which contains a DNA-dependent ATPase domain. We have isolated a human complementary DNA encoding a 205K nuclear protein, BRG1, that contains extensive homology to SWI2 and Drosophila brahma. We report here that a SWI2/BRG1 chimera with the DNA-dependent ATPase domain replaced by corresponding human sequence restored normal mitotic growth and capacity for transcriptional activation to swi2- yeast cells. Point mutation of the conserved ATP binding site lysine abolished this complementation. This mutation in SWI2 exerted a dominant negative effect on transcription in yeast. A lysine to arginine substitution at the corresponding residue of BRG1 also generated a transcriptional dominant negative in human cells. BRG1 is exclusively nuclear and present in a high M(r) complex of about 2 x 10(6). These results show that the SWI2 family DNA-dependent ATPase domain has functional conservation between yeast and humans and suggest that a SWI/SNF protein complex is required for the activation of selective mammalian genes.
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PMID:BRG1 contains a conserved domain of the SWI2/SNF2 family necessary for normal mitotic growth and transcription. 823 56

The yeast SWI2/SNF2 polypeptide is a subunit of the SWI/SNF protein complex that is required for many transcriptional activators to function in a chromatin context. SWI2 is believed to be the founding member of a new subfamily of DNA-stimulated ATPases/DNA helicases that includes proteins that function in DNA repair (RAD5, RAD16, ERCC6), recombination (RAD54), transcription (MOT1, ISWI, brm, BRG1, hBRM) and cell cycle control (STH1). We have created a set of 16 mutations within the SWI2 ATPase domain and have analyzed the functional consequences of these mutations in vivo. We have identified residues within each of the seven ATPase motifs that are required for SWI2 function. We have also identified crucial residues that are interspersed between the known ATPase motifs. In contrast, we identify other highly conserved residues that appear to be dispensable for SWI2 function. We also find that single amino acid changes in ATPase motifs IV and VI lead to a dominant negative phenotype. None of the 12 SWI2 mutations that disrupt SWI2 activity in vivo alter the assembly of the SWI/SNF complex. These studies provide an invaluable framework for biochemical analysis of the SWI2 ATPase and for functional analysis of other SWI2 family members.
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PMID:Functional analysis of the DNA-stimulated ATPase domain of yeast SWI2/SNF2. 887 45

A novel 15-subunit complex with the capacity to remodel the structure of chromatin, termed RSC, has been isolated from S. cerevisiae on the basis of homology to the SWI/SNF complex. At least three RSC subunits are related to SWI/SNF polypeptides: Sth1p, Rsc6p, and Rsc8p are significantly similar to Swi2/Snf2p, Swp73p, and Swi3p, respectively, and were identified by mass spectrometric and sequence analysis of peptide fragments. Like SWI/SNF, RSC exhibits a DNA-dependent ATPase activity stimulated by both free and nucleosomal DNA and a capacity to perturb nucleosome structure. RSC is, however, at least 10-fold more abundant than SWI/SNF complex and is essential for mitotic growth. Contrary to a report for SWII/SNF complex, no association of RSC (nor of SWI/SNF complex) with RNA polymerase II holoenzyme was detected.
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PMID:RSC, an essential, abundant chromatin-remodeling complex. 898 Feb 31

The human SNF2alpha (or hbrm) and SNF2beta (or BRG1) proteins have previously been shown to enhance transcriptional activation by nuclear receptors (NRs) in cultured human cells, and to be present in SWI/SNF complexes which are thought to be involved in control of transcription by facilitating remodelling of chromatin templates. Using the yeast two-hybrid system, we now demonstrate that the N-terminal regions of hSNF2alpha and hSNF2beta, preceding the DNA-dependent ATPase domain, specifically interact with the region of the estrogen receptor (ER) which includes the ligand binding domain and the ligand-dependent activation function AF-2. These interactions are increased by estrogen, but not by the ER AF-2 antagonist hydroxytamoxifen. Furthermore, mutants of ER that lack AF-2 activity are unable to interact with hSNF2alpha and -beta. These results suggest that the human homologues of the yeast SWI2/SNF2 protein may participate in the enhancement of transcription by the ER in vivo through interactions with the AF-2 activating domain, thus leading to ligand-dependent remodelling of chromatin templates.
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PMID:Ligand-dependent interaction between the estrogen receptor and the human homologues of SWI2/SNF2. 909 65

The brm and BRG-1 proteins are mutually exclusive subunits of the mammalian SWI-SNF complex. Within this complex, they provide the ATPase activity necessary for transcriptional regulation by nucleosome disruption. Both proteins were recently found to interact with the p105Rb tumor suppressor gene product, suggesting a role for the mammalian SWI-SNF complex in the control of cell growth. We show here that the expression of brm, but not BRG-1, is negatively regulated by mitogenic stimulation, and that growth arrest of mouse fibroblasts leads to increased accumulation of the brm protein. The expression of this protein is also down-regulated upon transformation by the ras oncogene. Re-introduction of brm into ras transformed cells leads to partial reversion of the transformed phenotype by a mechanism that depends on the ATPase domain of the protein. Our data suggest that increased levels of brm protein favour the withdrawal of the cell from the cycle whereas decreased expression of the brm gene may facilitate cellular transformation by various oncogenes.
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PMID:ras transformation is associated with decreased expression of the brm/SNF2alpha ATPase from the mammalian SWI-SNF complex. 942 56

Chromatin is a dynamic material; chromatin structures can repress transcription and their remodeling accompanies activation. Recent biochemical studies in Drosophila have revealed three multi-protein complexes with ATP-dependent chromatin restructuring activities. Although all contain the ATPase ISWI, their properties in vitro are markedly different, distinct from SWI-SNF and reveal intriguing connections to both transcription and chromatin assembly.
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PMID:Chromatin remodeling machines: similar motors, ulterior motives. 947 31


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