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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

We have isolated a human cDNA clone encoding HIP116, a protein that binds to the SPH repeats of the SV40 enhancer and to the TATA/inhibitor region of the human immunodeficiency virus (HIV)-1 promoter. The predicted HIP116 protein is related to the yeast SNF2/SWI2 transcription factor and to other members of this extended family and contains seven domains similar to those found in the vaccinia NTP1 ATPase. Interestingly, HIP116 also contains a C3HC4 zinc-binding motif (RING finger) interspersed between the ATPase motifs in an arrangement similar to that found in the yeast RAD5 and RAD16 proteins. The HIP116 amino terminus is unique among the members of this family, and houses a specific DNA-binding domain. Antiserum raised against HIP116 recognizes a 116-kDa nuclear protein in Western blots and specifically supershifts SV40 and HIV-1 protein-DNA complexes in gel shift experiments. The binding site for HIP116 on the SV40 enhancer directly overlaps the site for TEF-1, and like TEF-1, binding of HIP116 to the SV40 enhancer is destroyed by mutations that inhibit SPH enhancer activity in vivo. Purified fractions of HIP116 display strong ATPase activity that is preferentially stimulated by SPH DNA and can be inhibited specifically by antibodies to HIP116. These findings suggest that HIP116 might affect transcription, directly or indirectly, by acting as a DNA binding site-specific ATPase.
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PMID:Cloning of an SNF2/SWI2-related protein that binds specifically to the SPH motifs of the SV40 enhancer and to the HIV-1 promoter. 787 28

The Drosophila brahma (brm) gene encodes an activator of homeotic genes that is highly related to the yeast transcriptional activator SWI2 (SNF2), a potential helicase. To determine whether brm is a functional homolog of SWI2 or merely a member of a family of SWI2-related genes, we searched for additional Drosophila genes related to SWI2 and examined their function in yeast cells. In addition to brm, we identified one other Drosophila relative of SWI2: the closely related ISWI gene. The 1,027-residue ISWI protein contains the DNA-dependent ATPase domain characteristic of the SWI2 protein family but lacks the three other domains common to brm and SWI2. In contrast, the ISWI protein is highly related (70% identical) to the human hSNF2L protein over its entire length, suggesting that they may be functional homologs. The DNA-dependent ATPase domains of brm and SWI2, but not ISWI, are functionally interchangeable; a chimeric SWI2-brm protein partially rescued the slow growth of swi2- cells and supported transcriptional activation mediated by the glucocorticoid receptor in vivo in yeast cells. These findings indicate that brm is the closest Drosophila relative of SWI2 and suggest that brm and SWI2 play similar roles in transcriptional activation.
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PMID:Identification and characterization of Drosophila relatives of the yeast transcriptional activator SNF2/SWI2. 790 17

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

A complex containing the products of the SWI1/ADR6, SWI2/SNF2, SWI3, SNF5, and SNF6 genes and four additional polypeptides has been purified from extracts of the yeast Saccharomyces cerevisiae. Physical association of these proteins was demonstrated by copurification and coimmunoprecipitation. A potent DNA-dependent ATPase copurified with the complex, and this activity was evidently associated with SWI2/SNF2.
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PMID:A multisubunit complex containing the SWI1/ADR6, SWI2/SNF2, SWI3, SNF5, and SNF6 gene products isolated from yeast. 812 13

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 SNF2 (SWI2) protein functions with SNF5, SNF6, SWI1, and SWI3 in the transcriptional activation of many differently regulated genes. These proteins appear to facilitate activation by gene-specific regulatory proteins. SNF2 is highly conserved among eukaryotes and defines a family of proteins with similarity to helicases and nucleic acid-dependent NTPases. Here, we present genetic and biochemical evidence that SNF2 has DNA-stimulated ATPase activity. Mutations in the nucleoside triphosphate (NTP)-binding motif and other conserved motifs impair SNF2 function. Swapping experiments with another member of this family indicate that the helicase-related domains are functionally interchangeable. Finally, bacterially expressed SNF2 protein has ATPase activity that is stimulated by double-stranded DNA, and mutation of the NTP-binding site abolishes this activity. Deletion analysis shows that the helicase-like region of SNF2 is necessary, but not sufficient, for transcriptional activation.
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PMID:The yeast SNF2/SWI2 protein has DNA-stimulated ATPase activity required for transcriptional activation. 845 75

We report the purification of an ATP-dependent nucleosome remodeling factor (NURF) from Drosophila embryo extracts. NURF is composed of at least four polypeptides that act in concert with the GAGA transcription factor to alter chromatin structure at the hsp70 promoter. The energy requirement is attributed to an ATPase activity that is stimulated by nucleosomes but not by free DNA or histones, suggesting that NURF acts directly on a nucleosome to perturb its structure. This finding and the physical properties of NURF contrast sharply with the multisubunit SWI2/SNF2 complex, which has also been shown to alter nucleosomes in an ATP-dependent manner. The results suggest that two distinct systems may be involved in remodeling chromatin for transcription.
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PMID:Purification and properties of an ATP-dependent nucleosome remodeling factor. 852 1

The generation of an accessible heat shock promoter in chromatin in vitro requires the concerted action of the GAGA transcription factor and NURF, an ATP-dependent nucleosome remodeling factor. NURF is composed of four subunits and is biochemically distinct from the SWI2/SNF2 multiprotein complex, a transcriptional activator that also appears to alter nucleosome structure. We have obtained protein microsequence and immunological evidence identifying the 140 kDa subunit of NURF as ISWI, previously of unknown function but highly related to SWI2/SNF2 only in the ATPase domain. The ISWI protein is localized to the cell nucleus and is expressed throughout Drosophila development at levels as high as 100,000 molecules/cell. The convergence of biochemical and genetic studies on ISWI and SWI2/SNF2 underscores these ATPases and their close relatives as key components of independent systems for chromatin remodeling.
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PMID:ISWI, a member of the SWI2/SNF2 ATPase family, encodes the 140 kDa subunit of the nucleosome remodeling factor. 852 2


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