scholarly journals A Role for Groucho Tetramerization in Transcriptional Repression

1998 ◽  
Vol 18 (12) ◽  
pp. 7259-7268 ◽  
Author(s):  
Guoqing Chen ◽  
Pierre H. Nguyen ◽  
Albert J. Courey
Keyword(s):  
Transcriptional Repression ◽  
Fusion Proteins ◽  
Leucine Zipper ◽  
Point Mutations ◽  
Cross Linking ◽  
Transcriptional Repressors ◽  
Terminal Domain ◽  
Tetramerization Domain ◽  
Repeat Domain ◽  
Eukaryotic Organisms

ABSTRACT The Drosophila Groucho (Gro) protein is a corepressor required by a number of DNA-binding transcriptional repressors. Comparison of Gro with its homologues in other eukaryotic organisms reveals that Gro contains, in addition to a conserved C-terminal WD repeat domain, a conserved N-terminal domain, which has previously been implicated in transcriptional repression. We determined, via a variety of hydrodynamic measurements as well as protein cross-linking, that native Gro is a tetramer in solution and that tetramerization is mediated by two putative amphipathic α-helices (termed leucine zipper-like motifs) found in the N-terminal region. Point mutations in the leucine zipper-like motifs that block tetramerization also block repression by Gro, as assayed in cultured Drosophila cells with Gal4-Gro fusion proteins. Furthermore, the heterologous tetramerization domain from p53 fully substitutes for the Gro tetramerization domain in transcriptional repression. These findings suggest that oligomerization is essential for Gro-mediated repression and that the primary function of the conserved N-terminal domain is to mediate this oligomerization.

scholarly journals The Leucine Zipper Motif of the Drosophila AF10 Homologue Can Inhibit PRE-Mediated Repression: Implications for Leukemogenic Activity of Human MLL-AF10 Fusions

2003 ◽  
Vol 23 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Laurent Perrin ◽  
Sébastien Bloyer ◽  
Conchita Ferraz ◽  
Namita Agrawal ◽  
Pradip Sinha ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Transcriptional Repression ◽  
Fusion Proteins ◽  
Leucine Zipper ◽  
Full Length ◽  
Fusion Partner ◽  
Leucine Zipper Motif ◽  
Dominant Mutation ◽  
Leucine Zipper Domain ◽  
Phd Domain

ABSTRACT In a screen for Drosophila genes that interfere with transcriptional repression mediated by the Polycomb group of genes, we identified a dominant mutation affecting the Alhambra (Alh) gene, the fly homologue of the human AF10 gene. AF10 has been identified as a fusion partner of both MLL and CALM in infant leukemias. Both fusion proteins retain the leucine zipper domain of AF10 but not its PHD domain. We show here that, while the full-length ALH protein has no activity on Polycomb group-responsive elements (PREs), overexpression of the isolated ALH leucine zipper domain activates several PREs. Within the ALH full-length protein, the PHD domain inhibits the PRE deregulation mediated by the leucine zipper domain. This deregulation is conserved in the human AF10 leucine zipper domain, which confers the same activity on an oncogenic MLL-AF10 fusion protein expressed in Drosophila melanogaster. These data reveal new properties for the leucine zipper domain and thus might provide new clues to understanding the mechanisms by which AF10 fusion proteins in which the PHD domain is lost might trigger leukemias in humans.

scholarly journals Activation and repression by the C-terminal domain of Dorsal

Development ◽  
2001 ◽  
Vol 128 (10) ◽  
pp. 1869-1879 ◽  
Author(s):  
R.D. Flores-Saaib ◽  
S. Jia ◽  
A.J. Courey
Keyword(s):  
Fusion Protein ◽  
Concentration Gradient ◽  
Binding Sites ◽  
Transcriptional Repression ◽  
Fusion Proteins ◽  
Drosophila Embryo ◽  
Terminal Domain ◽  
Localization Signal ◽  
Pattern Forming ◽  
Rel Homology Domain

In the Drosophila embryo, Dorsal, a maternally expressed Rel family transcription factor, regulates dorsoventral pattern formation by activating and repressing zygotically active fate-determining genes. Dorsal is distributed in a ventral-to-dorsal nuclear concentration gradient in the embryo, the formation of which depends upon the spatially regulated inhibition of Dorsal nuclear uptake by Cactus. Using maternally expressed Gal4/Dorsal fusion proteins, we have explored the mechanism of activation and repression by Dorsal. We find that a fusion protein containing the Gal4 DNA-binding domain fused to full-length Dorsal is distributed in a nuclear concentration gradient that is similar to that of endogenous Dorsal, despite the presence of a constitutively active nuclear localization signal in the Gal4 domain. Whether this fusion protein activates or represses reporter genes depends upon the context of the Gal4-binding sites in the reporter. A Gal4/Dorsal fusion protein lacking the conserved Rel homology domain of Dorsal, but containing the non-conserved C-terminal domain also mediates both activation and repression, depending upon Gal4-binding site context. A region close to the C-terminal end of the C-terminal domain has homology to a repression motif in Engrailed - the eh1 motif. Deletion analysis indicates that this region mediates transcriptional repression and binding to Groucho, a co-repressor known to be required for Dorsal-mediated repression. As has previously been shown for repression by Dorsal, we find that activation by Dorsal, in particular by the C-terminal domain, is modulated by the maternal terminal pattern-forming system.

The Development of Inhibitors Targeting the Mixed Lineage Leukemia 1 (MLL1)-WD Repeat Domain 5 Protein (WDR5) Protein- Protein Interaction

2020 ◽  
Vol 27 (33) ◽  
pp. 5530-5542
Author(s):  
Xiaoqing Ye ◽  
Gang Chen ◽  
Jia Jin ◽  
Binzhong Zhang ◽  
Yinda Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Interaction ◽  
Fusion Proteins ◽  
Recent Progress ◽  
Mixed Lineage Leukemia ◽  
Core Complex ◽  
Histone Methyltransferases ◽  
Protein Protein Interaction ◽  
Histone 3 ◽  
Repeat Domain

Mixed Lineage Leukemia 1 (MLL1), an important member of Histone Methyltransferases (HMT) family, is capable of catalyzing mono-, di-, and trimethylation of Histone 3 lysine 4 (H3K4). The optimal catalytic activity of MLL1 requires the formation of a core complex consisting of MLL1, WDR5, RbBP5, and ASH2L. The Protein-Protein Interaction (PPI) between WDR5 and MLL1 plays an important role in abnormal gene expression during tumorigenesis, and disturbing this interaction may have a potential for the treatment of leukemia harboring MLL1 fusion proteins. In this review, we will summarize recent progress in the development of inhibitors targeting MLL1- WDR5 interaction.

scholarly journals The Carboxy-Terminal Domain of Glycoprotein N of Human Cytomegalovirus Is Required for Virion Morphogenesis

2007 ◽  
Vol 81 (10) ◽  
pp. 5212-5224 ◽  
Author(s):  
Michael Mach ◽  
Karolina Osinski ◽  
Barbara Kropff ◽  
Ursula Schloetzer-Schrehardt ◽  
Magdalena Krzyzaniak ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Critical Role ◽  
Point Mutations ◽  
Cysteine Residue ◽  
Cysteine Residues ◽  
Type I ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Carboxy Terminal ◽  
Assembly Compartment

ABSTRACT Glycoproteins M and N (gM and gN, respectively) are among the few proteins that are conserved across the herpesvirus family. The function of the complex is largely unknown. Whereas deletion from most alphaherpesviruses has marginal effects on the replication of the respective viruses, both proteins are essential for replication of human cytomegalovirus (HCMV). We have constructed a series of mutants in gN to study the function of this protein. gN of HCMV is a type I glycoprotein containing a short carboxy-terminal domain of 14 amino acids, including two cysteine residues directly adjacent to the predicted transmembrane anchor at positions 125 and 126. Deletion of the entire carboxy-terminal domain as well as substitution with the corresponding region from alpha herpesviruses or mutations of both cysteine residues resulted in a replication-incompetent virus. Recombinant viruses containing point mutations of either cysteine residue could be generated. These viruses were profoundly defective for replication. Complex formation of the mutant gNs with gM and transport of the complex to the viral assembly compartment appeared unaltered compared to the wild type. However, in infected cells, large numbers of capsids accumulated in the cytoplasm that failed to acquire an envelope. Transiently expressed gN was shown to be modified by palmitic acid at both cysteine residues. In summary, our data suggest that the carboxy-terminal domain of gN plays a critical role in secondary envelopment of HCMV and that palmitoylation of gN appears to be essential for function in secondary envelopment of HCMV and virus replication.

Association of the brain anion exchanger, AE3, with the repeat domain of ankyrin

1993 ◽  
Vol 105 (4) ◽  
pp. 1137-1142 ◽  
Author(s):  
C.W. Morgans ◽  
R.R. Kopito
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Anion Exchanger ◽  
Deletion Mutant ◽  
Tandem Repeats ◽  
Structural Homology ◽  
Terminal Domain ◽  
Repeat Domain ◽  
The Brain

The 89 kDa NH2-terminal domain of erythrocyte ankyrin is composed almost entirely of 22 tandem repeats of a 33 amino acid sequence and constitutes the binding site for the cytoplasmic NH2-terminal domain of the erythrocyte anion exchanger, AE1. We have developed an assay to evaluate the in vivo interaction between a fragment of ankyrin corresponding to this domain (ANK90) and two non-erythroid anion exchangers, AE2 and AE3, that share considerable structural homology with AE1. Association was assessed by co-immunoprecipitation of ANK90-anion exchanger complexes from detergent extracts of cells cotransfected with plasmids encoding the ankyrin fragment and the anion exchanger or mutants thereof. ANK90 was co-immunoprecipitated with AE1 but not with an AE1 deletion mutant lacking the cytoplasmic NH2-terminal domain. Using this assay, we show that the brain anion exchanger AE3, but not the closely related homologue, AE2, is capable of binding to ankyrin.

scholarly journals A Recombinant Carboxy-Terminal Domain of the Protective Antigen of Bacillus anthracis Protects Mice against Anthrax Infection

2002 ◽  
Vol 70 (3) ◽  
pp. 1653-1656 ◽  
Author(s):  
Helen C. Flick-Smith ◽  
Nicola J. Walker ◽  
Paula Gibson ◽  
Helen Bullifent ◽  
Sarah Hayward ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Fusion Proteins ◽  
Protective Antigen ◽  
Protective Efficacy ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Anthrax Infection ◽  
Carboxy Terminal ◽  
Domain 4

ABSTRACT The immunogenicity and protective efficacy of overlapping regions of the protective antigen (PA) polypeptide, cloned and expressed as glutathione S-transferase fusion proteins, have been assessed. Results show that protection can be attributed to individual domains and imply that it is domain 4 which contains the dominant protective epitopes of PA.

scholarly journals Transcriptional repression by Drosophila and mammalian Polycomb group proteins in transfected mammalian cells.

1994 ◽  
Vol 14 (3) ◽  
pp. 1721-1732 ◽  
Author(s):  
C A Bunker ◽  
R E Kingston
Keyword(s):  
Binding Sites ◽  
Transcriptional Repression ◽  
Fusion Proteins ◽  
Mammalian Cells ◽  
Polycomb Group ◽  
Polycomb Group Proteins ◽  
Related Gene ◽  
Activation Domains ◽  
Sex Combs ◽  
Significant Homology

The Polycomb group (Pc-G) genes are essential for maintaining the proper spatially restricted expression pattern of the homeotic loci during Drosophila development. The Pc-G proteins appear to function at target loci to maintain a state of transcriptional repression. The murine oncogene bmi-1 has significant homology to the Pc-G gene Posterior sex combs (Psc) and a highly related gene, Suppressor two of zeste [Su(z)2]. We show here that the proteins encoded by bmi-1 and the Pc-G genes Polycomb (Pc) and Psc as well as Su(z)2 mediate repression in mammalian cells when targeted to a promoter by LexA in a cotransfection system. These fusion proteins repress activator function by as much as 30-fold, and the effect on different activation domains is distinct for each Pc-G protein. Repression is observed when the LexA fusion proteins are bound directly adjacent to activator binding sites and also when bound 1,700 bases from the promoter. These data demonstrate that the products of the Pc-G genes can significantly repress activator function on transiently introduced DNA. We suggest that this function contributes to the stable repression of targeted loci during development.

scholarly journals Widespread microRNA degradation elements in target mRNAs can assist the encoded proteins

2021 ◽  
Author(s):  
Lu Li ◽  
Peike Sheng ◽  
Tianqi Li ◽  
Christopher J. Fields ◽  
Nicholas M. Hiers ◽  
...  
Keyword(s):  
Gene Expression ◽  
Ubiquitin Ligase ◽  
Transcriptional Repression ◽  
Mirna Target ◽  
Cross Linking ◽  
Base Pairing ◽  
Proapoptotic Protein ◽  
Nucleotide Addition ◽  
Mirna Degradation ◽  
Target Rna

Binding of microRNAs (miRNAs) to mRNAs normally results in post-transcriptional repression of gene expression. However, extensive base-pairing between miRNAs and target RNAs can trigger miRNA degradation, a phenomenon called target RNA-directed miRNA degradation (TDMD). Here, we systematically analyzed Argonaute-CLASH (cross-linking, ligation, and sequencing of miRNA–target RNA hybrids) data and identified numerous candidate TDMD triggers, focusing on their ability to induce nontemplated nucleotide addition at the miRNA 3′ end. When exogenously expressed in various cell lines, eight triggers induce degradation of corresponding miRNAs. Both the TDMD base-pairing and surrounding sequences are essential for TDMD. CRISPR knockout of endogenous trigger or ZSWIM8, a ubiquitin ligase essential for TDMD, reduced miRNA degradation. Furthermore, degradation of miR-221 and miR-222 by a trigger in BCL2L11, which encodes a proapoptotic protein, enhances apoptosis. Therefore, we uncovered widespread TDMD triggers in target RNAs and demonstrated an example that could functionally cooperate with the encoded protein.

scholarly journals Effect of peptide linker length and composition on immobilization and catalysis of leucine zipper-enzyme fusion proteins

AIChE Journal ◽  
2018 ◽  
Vol 64 (8) ◽  
pp. 2934-2946 ◽  
Author(s):  
Adam A. Caparco ◽  
Andreas S. Bommarius ◽  
Julie A. Champion
Keyword(s):  
Fusion Proteins ◽  
Leucine Zipper ◽  
Linker Length ◽  
Enzyme Fusion
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