9c4b
Second BAF53a of the human TIP60 complex
Structural highlights
DiseaseACL6A_HUMAN Non-specific syndromic intellectual disability. ACTL6A mutations have been found in patients with intellectual disability of variable severity, developmental delay, dysmorphic features and digit abnormalities. Additional features may include genitourinary and cardiac defects. The disease phenotype resembles Coffin-Siris syndrome and brachymorphism-onychodysplasia-dysphalangism syndrome.[1] FunctionACL6A_HUMAN Involved in transcriptional activation and repression of select genes by chromatin remodeling (alteration of DNA-nucleosome topology). Component of SWI/SNF chromatin remodeling complexes that carry out key enzymatic activities, changing chromatin structure by altering DNA-histone contacts within a nucleosome in an ATP-dependent manner. Required for maximal ATPase activity of SMARCA4/BRG1/BAF190A and for association of the SMARCA4/BRG1/BAF190A containing remodeling complex BAF with chromatin/nuclear matrix. Belongs to the neural progenitors-specific chromatin remodeling complex (npBAF complex) and is required for the proliferation of neural progenitors. During neural development a switch from a stem/progenitor to a postmitotic chromatin remodeling mechanism occurs as neurons exit the cell cycle and become committed to their adult state. The transition from proliferating neural stem/progenitor cells to postmitotic neurons requires a switch in subunit composition of the npBAF and nBAF complexes. As neural progenitors exit mitosis and differentiate into neurons, npBAF complexes which contain ACTL6A/BAF53A and PHF10/BAF45A, are exchanged for homologous alternative ACTL6B/BAF53B and DPF1/BAF45B or DPF3/BAF45C subunits in neuron-specific complexes (nBAF). The npBAF complex is essential for the self-renewal/proliferative capacity of the multipotent neural stem cells. The nBAF complex along with CREST plays a role regulating the activity of genes essential for dendrite growth (By similarity). Component of the NuA4 histone acetyltransferase (HAT) complex which is involved in transcriptional activation of select genes principally by acetylation of nucleosomal histones H4 and H2A. This modification may both alter nucleosome - DNA interactions and promote interaction of the modified histones with other proteins which positively regulate transcription. This complex may be required for the activation of transcriptional programs associated with oncogene and proto-oncogene mediated growth induction, tumor suppressor mediated growth arrest and replicative senescence, apoptosis, and DNA repair. NuA4 may also play a direct role in DNA repair when recruited to sites of DNA damage. Putative core component of the chromatin remodeling INO80 complex which is involved in transcriptional regulation, DNA replication and probably DNA repair.[UniProtKB:Q9Z2N8][2] [3] [4] [5] [6] Publication Abstract from PubMedThe human NuA4/TIP60 co-activator complex, a fusion of the yeast SWR1 and NuA4 complexes, both incorporates the histone variant H2A.Z into nucleosomes and acetylates histones H4/H2A/H2A.Z to regulate gene expression and maintain genome stability. Our cryo-electron microscopy studies show that, within the NuA4/TIP60 complex, the EP400 subunit serves as a scaffold holding the different functional modules in specific positions, creating a unique arrangement of the ARP module. EP400 interacts with the TRRAP subunit using a footprint that overlaps with that of the SAGA acetyltransferase complex, preventing the formation of a hybrid complex. Loss of the TRRAP subunit leads to mislocalization of NuA4/TIP60, resulting in the redistribution of H2A.Z and its acetylation across the genome, emphasizing the dual functionality of NuA4/TIP60 as a single macromolecular assembly. Structural insights into the human NuA4/TIP60 acetyltransferase and chromatin remodeling complex.,Yang Z, Mameri A, Cattoglio C, Lachance C, Florez Ariza AJ, Luo J, Humbert J, Sudarshan D, Banerjea A, Galloy M, Fradet-Turcotte A, Lambert JP, Ranish JA, Cote J, Nogales E Science. 2024 Aug 1:eadl5816. doi: 10.1126/science.adl5816. PMID:39088653[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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