5tgc | pdb_00005tgc
Structure of the hetero-trimer of Rtt102-Arp7/9 bound to ATP
Structural highlights
FunctionARP7_YEAST Component of the chromatin structure remodeling complex (RSC), which is involved in transcription regulation and nucleosome positioning. RSC is responsible for the transfer of a histone octamer from a nucleosome core particle to naked DNA. The reaction requires ATP and involves an activated RSC-nucleosome intermediate. Remodeling reaction also involves DNA translocation, DNA twist and conformational change. As a reconfigurer of centromeric and flanking nucleosomes, RSC complex is required both for proper kinetochore function in chromosome segregation and, via a PKC1-dependent signaling pathway, for organization of the cellular cytoskeleton. This subunit is involved in transcriptional regulation. Heterodimer of ARP7 and ARP9 functions with HMG box proteins to facilitate proper chromatin architecture. Heterodimer formation is necessary for assembly into RSC complex. Part of the SWI/SNF complex, an ATP-dependent chromatin remodeling complex, is required for the positive and negative regulation of gene expression of a large number of genes. It changes chromatin structure by altering DNA-histone contacts within a nucleosome, leading eventually to a change in nucleosome position, thus facilitating or repressing binding of gene-specific transcription factors.[1] [2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedThe catalytic subunits of SWI/SNF-family and INO80-family chromatin remodelers bind actin and actin-related proteins (Arps) through an N-terminal helicase/SANT-associated (HSA) domain. Between the HSA and ATPase domains lies a conserved post-HSA (pHSA) domain. The HSA domain of Sth1, the catalytic subunit of the yeast SWI/SNF-family remodeler RSC, recruits the Rtt102-Arp7/9 heterotrimer. Rtt102-Arp7/9 regulates RSC function, but the mechanism is unclear. We show that the pHSA domain interacts directly with another conserved region of the catalytic subunit, protrusion-1. Rtt102-Arp7/9 binding to the HSA domain weakens this interaction and promotes the formation of stable, monodisperse complexes with DNA and nucleosomes. A crystal structure of Rtt102-Arp7/9 shows that ATP binds to Arp7 but not Arp9. However, Arp7 does not hydrolyze ATP. Together, the results suggest that Rtt102 and ATP stabilize a conformation of Arp7/9 that potentiates binding to the HSA domain, which releases intramolecular interactions within Sth1 and controls DNA and nucleosome binding. Actin-related proteins regulate the RSC chromatin remodeler by weakening intramolecular interactions of the Sth1 ATPase.,Turegun B, Baker RW, Leschziner AE, Dominguez R Commun Biol. 2018;1. doi: 10.1038/s42003-017-0002-6. Epub 2018 Jan 22. PMID:29809203[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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