Insights into the structure of the CCR4-NOT complex by electron microscopy

European Molecular Biology Laboratory, (EMBL), Heidelberg, Germany.
FEBS letters (Impact Factor: 3.34). 06/2011; 585(14):2182-6. DOI: 10.1016/j.febslet.2011.05.071
Source: PubMed

ABSTRACT The CCR4-NOT complex is a deadenylation complex, which plays a major role for mRNA stability. The complex is conserved from yeast to human and consists of nine proteins NOT1-NOT5, CCR4, CAF1, CAF40 and CAF130. We have successfully isolated the complex using a Protein A tag on NOT1, followed by cross-linking on a glycerol gradient. All components of the complex were identified by mass spectrometry. Electron microscopy of negatively stained particles followed by image reconstruction revealed an L-shaped complex with two arms of similar length. The arms form an accessible cavity, which we think could provide an extensive interface for RNA-deadenylation.

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    ABSTRACT: The CCR4-NOT complex is a highly conserved, multifunctional machinery with a general role in controlling mRNA metabolism. It has been implicated in a number of different aspects of mRNA and protein expression, including mRNA degradation, transcription initiation and elongation, ubiquitination, and protein modification. The core CCR4-NOT complex is evolutionarily conserved and consists of at least three NOT proteins and two catalytic subunits. The L-shaped complex is characterized by two functional modules bound to the CNOT1/Not1 scaffold protein: the deadenylase or nuclease module containing two enzymes required for deadenylation, and the NOT module. In this review, we will summarize the currently available information regarding the three-dimensional structure and assembly of the CCR4-NOT complex, in order to provide insight into its roles in mRNA degradation and other biological processes.
    Frontiers in Genetics 05/2014; 5:137. DOI:10.3389/fgene.2014.00137
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    ABSTRACT: The CCR4–NOT complex is a multi-subunit protein complex evolutionarily conserved across eukaryotes which regulates several aspects of gene expression. A fascinating model is emerging in which this complex acts as a regulation platform, controlling gene products ‘from birth to death’ through the coordination of different cellular machineries involved in diverse cellular functions. Recently the CCR4–NOT functions have been extended to the control of the innate immune response through the regulation of interferon signaling. Thus, a more comprehensive picture of how CCR4–NOT allows the rapid adaptation of cells to external stress, from transcription to mRNA and protein decay, is presented and discussed here. Overall, CCR4–NOT permits the efficient and rapid adaptation of cellular gene expression in response to changes in environmental conditions and stimuli.For further resources related to this article, please visit the WIREs website.Conflict of interest: The authors have declared no conflicts of interest for this article.
    WIREs RNA 11/2014; 5(6). DOI:10.1002/wrna.1254 · 6.15 Impact Factor
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    ABSTRACT: Controlled shortening of the poly(A) tail of mRNAs is the first step in eukaryotic mRNA decay and can also be used for translational inactivation of mRNAs. The CCR4-NOT complex is the most important among a small number of deadenylases, enzymes catalyzing poly(A) tail shortening. Rates of poly(A) shortening differ between mRNAs as the CCR4-NOT complex is recruited to specific mRNAs by means of either sequence-specific RNA binding proteins or miRNAs. This review summarizes our current knowledge concerning the subunit composition and deadenylation activity of the Drosophila CCR4-NOT complex and the mechanisms by which the complex is recruited to particular mRNAs. We discuss genetic data implicating the complex in the regulation of specific mRNAs, in particular in the context of development.
    Frontiers in Genetics 05/2014; 5:143. DOI:10.3389/fgene.2014.00143

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