scholarly journals The Drosophila Brahma complex is an essential coactivator for the trithorax group protein Zeste

2000 ◽  
Vol 14 (9) ◽  
pp. 1058-1071 ◽  
Author(s):  
Arnoud J. Kal ◽  
Tokameh Mahmoudi ◽  
Naomi B. Zak ◽  
C. Peter Verrijzer
Keyword(s):  
Chromatin Remodeling ◽  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Homeotic Genes ◽  
Trithorax Group ◽  
Trxg Protein ◽  
Chromatin Remodeling Complex ◽  
Direct Binding ◽  
Group Protein ◽  
Brahma Complex

The trithorax group (trxG) of activators andPolycomb group (PcG) of repressors are believed to control the expression of several key developmental regulators by changing the structure of chromatin. Here, we have sought to dissect the requirements for transcriptional activation by the DrosophilatrxG protein Zeste, a DNA-binding activator of homeotic genes. Reconstituted transcription reactions established that the Brahma (BRM) chromatin-remodeling complex is essential for Zeste-directed activation on nucleosomal templates. Because it is not required for Zeste to bind to chromatin, the BRM complex appears to act after promoter binding by the activator. Purification of the Drosophila BRM complex revealed a number of novel subunits. We found that Zeste tethers the BRM complex via direct binding to specific subunits, including trxG proteins Moira (MOR) and OSA. The leucine zipper of Zeste mediates binding to MOR. Interestingly, although the Imitation Switch (ISWI) remodelers are potent nucleosome spacing factors, they are dispensable for transcriptional activation by Zeste. Thus, there is a distinction between general chromatin restructuring and transcriptional coactivation by remodelers. These results establish that different chromatin remodeling factors display distinct functional properties and provide novel insights into the mechanism of their targeting.

scholarly journals The trithorax Group Genemoira Encodes a Brahma-Associated Putative Chromatin-Remodeling Factor in Drosophila melanogaster

1999 ◽  
Vol 19 (2) ◽  
pp. 1159-1170 ◽  
Author(s):  
Madeline A. Crosby ◽  
Chaya Miller ◽  
, Tamar Alon ◽  
Kellie L. Watson ◽  
C. Peter Verrijzer ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Chromatin Remodeling ◽  
Leucine Zipper ◽  
Genetic Relationships ◽  
Fruit Fly ◽  
Protein Product ◽  
Homeotic Genes ◽  
Trithorax Group ◽  
Functional Relationships

ABSTRACT The genes of the trithorax group (trxG) inDrosophila melanogaster are required to maintain the pattern of homeotic gene expression that is established early in embryogenesis by the transient expression of the segmentation genes. The precise role of each of the diverse trxG members and the functional relationships among them are not well understood. Here, we report on the isolation of the trxG gene moira(mor) and its molecular characterization. morencodes a fruit fly homolog of the human and yeast chromatin-remodeling factors BAF170, BAF155, and SWI3. mor is widely expressed throughout development, and its 170-kDa protein product is present in many embryonic tissues. In vitro, MOR can bind to itself and it interacts with Brahma (BRM), an SWI2-SNF2 homolog, with which it is associated in embryonic nuclear extracts. The leucine zipper motif of MOR is likely to participate in self-oligomerization; the equally conserved SANT domain, for which no function is known, may be required for optimal binding to BRM. MOR thus joins BRM and Snf5-related 1 (SNR1), two known Drosophila SWI-SNF subunits that act as positive regulators of the homeotic genes. These observations provide a molecular explanation for the phenotypic and genetic relationships among several of the trxG genes by suggesting that they encode evolutionarily conserved components of a chromatin-remodeling complex.

The Drosophila kismet gene is related to chromatin-remodeling factors and is required for both segmentation and segment identity

Development ◽  
1999 ◽  
Vol 126 (6) ◽  
pp. 1175-1187 ◽  
Author(s):  
G. Daubresse ◽  
R. Deuring ◽  
L. Moore ◽  
O. Papoulas ◽  
I. Zakrajsek ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Homeotic Genes ◽  
Loss Of Function ◽  
Larval Body ◽  
Sex Combs Reduced ◽  
Trithorax Group ◽  
Sex Combs ◽  
Pair Rule Gene ◽  
Body Segmentation ◽  
Group Protein

The Drosophila kismet gene was identified in a screen for dominant suppressors of Polycomb, a repressor of homeotic genes. Here we show that kismet mutations suppress the Polycomb mutant phenotype by blocking the ectopic transcription of homeotic genes. Loss of zygotic kismet function causes homeotic transformations similar to those associated with loss-of-function mutations in the homeotic genes Sex combs reduced and Abdominal-B. kismet is also required for proper larval body segmentation. Loss of maternal kismet function causes segmentation defects similar to those caused by mutations in the pair-rule gene even-skipped. The kismet gene encodes several large nuclear proteins that are ubiquitously expressed along the anterior-posterior axis. The Kismet proteins contain a domain conserved in the trithorax group protein Brahma and related chromatin-remodeling factors, providing further evidence that alterations in chromatin structure are required to maintain the spatially restricted patterns of homeotic gene transcription.

scholarly journals The Trithorax group protein ASH1 requires a combination of BAH domain and AT hooks, but not the SET domain, for mitotic chromatin binding and survival

Chromosoma ◽  
2021 ◽  
Author(s):  
Philipp A. Steffen ◽  
Christina Altmutter ◽  
Eva Dworschak ◽  
Sini Junttila ◽  
Attila Gyenesei ◽  
...  
Keyword(s):  
Transcriptional Profiling ◽  
Histone H3 ◽  
Chromatin Binding ◽  
Set Domain ◽  
Trithorax Group ◽  
Trxg Protein ◽  
Group Protein ◽  
Bah Domain ◽  
Mitotic Chromatin

AbstractThe Drosophila Trithorax group (TrxG) protein ASH1 remains associated with mitotic chromatin through mechanisms that are poorly understood. ASH1 dimethylates histone H3 at lysine 36 via its SET domain. Here, we identify domains of the TrxG protein ASH1 that are required for mitotic chromatin attachment in living Drosophila. Quantitative live imaging demonstrates that ASH1 requires AT hooks and the BAH domain but not the SET domain for full chromatin binding in metaphase, and that none of these domains are essential for interphase binding. Genetic experiments show that disruptions of the AT hooks and the BAH domain together, but not deletion of the SET domain alone, are lethal. Transcriptional profiling demonstrates that intact ASH1 AT hooks and the BAH domain are required to maintain expression levels of a specific set of genes, including several involved in cell identity and survival. This study identifies in vivo roles for specific ASH1 domains in mitotic binding, gene regulation, and survival that are distinct from its functions as a histone methyltransferase.

The trithorax group gene osa encodes an ARID-domain protein that genetically interacts with the brahma chromatin-remodeling factor to regulate transcription

Development ◽  
1999 ◽  
Vol 126 (4) ◽  
pp. 733-742 ◽  
Author(s):  
M. Vazquez ◽  
L. Moore ◽  
J.A. Kennison
Keyword(s):  
Gene Regulation ◽  
Chromatin Remodeling ◽  
Homeotic Gene ◽  
Dna Binding Domain ◽  
Atpase Subunit ◽  
Trithorax Group ◽  
Chromatin Remodeling Complex ◽  
P2 Promoter ◽  
Domain Protein ◽  
Arid Domain

The trithorax group gene brahma (brm) encodes the ATPase subunit of a chromatin-remodeling complex involved in homeotic gene regulation. We report here that brm interacts with another trithorax group gene, osa, to regulate the expression of the Antennapedia P2 promoter. Regulation of Antennapedia by BRM and OSA proteins requires sequences 5′ to the P2 promoter. Loss of maternal osa function causes severe segmentation defects, indicating that the function of osa is not limited to homeotic gene regulation. The OSA protein contains an ARID domain, a DNA-binding domain also present in the yeast SWI1 and Drosophila DRI proteins. We propose that the OSA protein may target the BRM complex to Antennapedia and other regulated genes.

scholarly journals The Swi/Snf Chromatin Remodeling Complex Is Required for Ribosomal DNA and Telomeric Silencing in Saccharomyces cerevisiae

2004 ◽  
Vol 24 (18) ◽  
pp. 8227-8235 ◽  
Author(s):  
Vardit Dror ◽  
Fred Winston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Chromatin Remodeling ◽  
Ribosomal Dna ◽  
Transcriptional Activation ◽  
Rdna Locus ◽  
Detectable Effect ◽  
Chromatin Remodeling Complex ◽  
Two Factors

ABSTRACT The Swi/Snf chromatin remodeling complex has been previously demonstrated to be required for transcriptional activation and repression of a subset of genes in Saccharomyces cerevisiae. In this work we demonstrate that Swi/Snf is also required for repression of RNA polymerase II-dependent transcription in the ribosomal DNA (rDNA) locus (rDNA silencing). This repression appears to be independent of both Sir2 and Set1, two factors known to be required for rDNA silencing. In contrast to many other rDNA silencing mutants that have elevated levels of rDNA recombination, snf2Δ mutants have a significantly decreased level of rDNA recombination. Additional studies have demonstrated that Swi/Snf is also required for silencing of genes near telomeres while having no detectable effect on silencing of HML or HMR.

Cap ‘n’ collar B cooperates with a small Maf subunit to specify pharyngeal development and suppress deformed homeotic function in the Drosophila head

Development ◽  
2000 ◽  
Vol 127 (18) ◽  
pp. 4023-4037 ◽  
Author(s):  
A. Veraksa ◽  
N. McGinnis ◽  
X. Li ◽  
J. Mohler ◽  
W. McGinnis
Keyword(s):  
Transcriptional Activation ◽  
Protein Function ◽  
Leucine Zipper ◽  
Suppressive Effect ◽  
Basic Leucine Zipper ◽  
Transcriptional Activation Domain ◽  
Amino Terminal ◽  
Culture Cells ◽  
Mandibular Segment ◽  
Direct Binding

The basic-leucine zipper protein Cap ‘n’ collar B (CncB) suppresses the segmental identity function of the Hox gene Deformed (Dfd) in the mandibular segment of Drosophila embryos. CncB is also required for proper development of intercalary, labral and mandibular structures. In this study, we provide evidence that the CncB-mediated suppression of Dfd requires the Drosophila homolog of the mammalian small Maf proteins, Maf-S, and that the suppression occurs even in the presence of high amounts of Dfd protein. Interestingly, the CncB/Maf-S suppressive effect can be partially reversed by overexpression of Homothorax (Hth), suggesting that Hth and Extradenticle proteins antagonize the effects of CncB/Maf-S on Dfd function in the mandibular segment. In embryos, multimers of simple CncB/Maf-S heterodimer sites are transcriptionally activated in response to CncB, and in tissue culture cells the amino-terminal domain of CncB acts as a strong transcriptional activation domain. There are no good matches to CncB/Maf binding consensus sites in the known elements that are activated in response to Dfd and repressed in a CncB-dependent fashion. This suggests that some of the suppressive effect of CncB/Maf-S proteins on Dfd protein function might be exerted indirectly, while some may be exerted by direct binding to as yet uncharacterized Dfd response elements. We also show that ectopic CncB is sufficient to transform ventral epidermis in the trunk into repetitive arrays of ventral pharynx. We compare the functions of CncB to those of its vertebrate and invertebrate homologs, p45 NF-E2, Nrf and Skn-1 proteins, and suggest that the pharynx selector function of CncB is highly conserved on some branches of the evolutionary tree.

scholarly journals Efg1-mediated Recruitment of NuA4 to Promoters Is Required for Hypha-specific Swi/Snf Binding and Activation inCandida albicans

2008 ◽  
Vol 19 (10) ◽  
pp. 4260-4272 ◽  
Author(s):  
Yang Lu ◽  
Chang Su ◽  
Xuming Mao ◽  
Prashna Pala Raniga ◽  
Haoping Liu ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Transcriptional Activation ◽  
Chromatin Immunoprecipitation ◽  
Pathogenic Fungus ◽  
Dependent Manner ◽  
Hyphal Development ◽  
Chromatin Remodeling Complex ◽  
A Subunit ◽  
Human Pathogenic Fungus ◽  
Incandida Albicans

Efg1 is essential for hyphal development and virulence in the human pathogenic fungus Candida albicans. How Efg1 regulates gene expression is unknown. Here, we show that Efg1 interacts with components of the nucleosome acetyltransferase of H4 (NuA4) histone acetyltransferase (HAT) complex in both yeast and hyphal cells. Deleting YNG2, a subunit of the NuA4 HAT module, results in a significant decrease in the acetylation level of nucleosomal H4 and a profound defect in hyphal development, as well as a defect in the expression of hypha-specific genes. Using chromatin immunoprecipitation, Efg1 and the NuA4 complex are found at the UAS regions of hypha-specific genes in both yeast and hyphal cells, and Efg1 is required for the recruitment of NuA4. Nucleosomal H4 acetylation at the promoters peaks during initial hyphal induction in an Efg1-dependent manner. We also find that Efg1 bound to the promoters of hypha-specific genes is critical for recruitment of the Swi/Snf chromatin remodeling complex during hyphal induction. Our data show that the recruitment of the NuA4 complex by Efg1 to the promoters of hypha-specific genes is required for nucleosomal H4 acetylation at the promoters during hyphal induction and for subsequent binding of Swi/Snf and transcriptional activation.

Nuclear receptor coactivators: the key to unlock chromatin

2005 ◽  
Vol 83 (4) ◽  
pp. 418-428 ◽  
Author(s):  
Wei Xu
Keyword(s):  
Nuclear Receptors ◽  
Nuclear Receptor ◽  
Chromatin Remodeling ◽  
Transcriptional Activation ◽  
Transcriptional Control ◽  
Biological Effects ◽  
Gene Activation ◽  
Nuclear Hormone Receptor ◽  
Nuclear Receptor Coactivators ◽  
Chromatin Remodeling Complex

The biological effects of hormones, ranging from organogenesis, metabolism, and proliferation, are transduced through nuclear receptors (NRs). Over the last decade, NRs have been used as a model to study transcriptional control. The conformation of activated NRs is favorable for the recruitment of coactivators, which promote transcriptional activation by directly communicating with chromatin. This review will focus on the function of different classes of coactivators and associated complexes, and on progress in our understanding of gene activation by NRs through chromatin remodeling.Key words: nuclear hormone receptor, p160 family of coactivators, histone modification, chromatin remodeling complex.

scholarly journals Interaction of Papillomavirus E2 Protein with the Brm Chromatin Remodeling Complex Leads to Enhanced Transcriptional Activation

2006 ◽  
Vol 81 (5) ◽  
pp. 2213-2220 ◽  
Author(s):  
R. Ajay Kumar ◽  
Samisubbu R. Naidu ◽  
Xiaoyu Wang ◽  
Anthony N. Imbalzano ◽  
Elliot J. Androphy
Keyword(s):  
Chromatin Remodeling ◽  
Transcriptional Activation ◽  
Potential Interaction ◽  
Transactivation Domain ◽  
Reporter System ◽  
Barr Virus ◽  
Amino Terminal ◽  
Chromatin Remodeling Complex ◽  
Epstein Barr

ABSTRACT Papillomavirus E2 is a sequence-specific DNA binding protein that regulates transcription and replication of the viral genome. The transcriptional activities of E2 are typically evaluated by transient transfection of nonreplicating E2-dependent reporters. We sought to address whether E2 activates transcription in an episomal context and its potential interaction with the chromatin remodeling proteins. Using an Epstein-Barr virus-based episomal reporter, we demonstrate that E2 stimulates transcription from an E2-dependent promoter in a chromatin context. This activation is enhanced by the presence of proteins associated with SWI/SNF complexes, which are ATP-dependent chromatin remodeling enzymes. We show that exogenous expression of the Brm ATPase enhances E2 activity in SWI/SNF-deficient cell lines and that the amino-terminal transactivation domain of E2 mediates association with the Brm complex in vivo. Using chromatin immunoprecipitation assays, we demonstrate that Brm enhances promoter occupancy by E2 in an episomal context. Our results demonstrate that E2 activates transcription from an episomal reporter system and reveal a novel property of E2 in collaborating with the Brm chromatin remodeling complex in enhancing transcriptional activation.

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