2h1e
Tandem chromodomains of budding yeast CHD1Tandem chromodomains of budding yeast CHD1
Structural highlights
FunctionCHD1_YEAST ATP-dependent chromatin-remodeling factor which functions as substrate recognition component of the transcription regulatory histone acetylation (HAT) complexes SAGA and SLIK. It recognizes H3K4me. SAGA is involved in RNA polymerase II-dependent transcriptional regulation of approximately 10% of yeast genes. At the promoters, SAGA is required for recruitment of the basal transcription machinery. It influences RNA polymerase II transcriptional activity through different activities such as TBP interaction (SPT3, SPT8 and SPT20) and promoter selectivity, interaction with transcription activators (GCN5, ADA2, ADA3 and TRA1), and chromatin modification through histone acetylation (GCN5) and deubiquitination (UBP8). SAGA acetylates nucleosomal histone H3 to some extent (to form H3K9ac, H3K14ac, H3K18ac and H3K23ac). SAGA interacts with DNA via upstream activating sequences (UASs). SLIK is proposed to have partly overlapping functions with SAGA. It preferentially acetylates methylated histone H3, at least after activation at the GAL1-10 locus. Acts in opposition to the FACT complex in regulating polymerase II transcription. Also required for efficient transcription by RNA polymerase I, and more specifically the pol I transcription termination step. Regulates negatively DNA replication. Not only involved in transcription-related chromatin-remodeling, but also required to maintain a specific chromatin configuration across the genome.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedDouble chromodomains occur in CHD proteins, which are ATP-dependent chromatin remodeling factors implicated in RNA polymerase II transcription regulation. Biochemical studies suggest important differences in the histone H3 tail binding of different CHD chromodomains. In human and Drosophila, CHD1 double chromodomains bind lysine 4-methylated histone H3 tail, which is a hallmark of transcriptionally active chromatin in all eukaryotes. Here, we present the crystal structure of the yeast CHD1 double chromodomains, and pinpoint their differences with that of the human CHD1 double chromodomains. The most conserved residues in these double chromodomains are the two chromoboxes that orient adjacently. Only a subset of CHD chromoboxes can form an aromatic cage for methyllysine binding, and methyllysine binding requires correctly oriented inserts. These factors preclude yeast CHD1 double chromodomains from interacting with the histone H3 tail. Despite great sequence similarity between the human CHD1 and CHD2 chromodomains, variation within an insert likely prevents CHD2 double chromodomains from binding lysine 4-methylated histone H3 tail as efficiently as in CHD1. By using the available structural and biochemical data we highlight the evolutionary specialization of CHD double chromodomains, and provide insights about their targeting capacities. Molecular implications of evolutionary differences in CHD double chromodomains.,Flanagan JF, Blus BJ, Kim D, Clines KL, Rastinejad F, Khorasanizadeh S J Mol Biol. 2007 Jun 1;369(2):334-42. Epub 2007 Mar 19. PMID:17433364[12] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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