title: Subunit Rtt102 controls the conformation of the Arp7/9 heterodimer and its interactions with nucleotide and the catalytic subunit of SWI/SNF remodelers.
abstract: Chromatin-remodeling complexes are assembled around a catalytic subunit that contains a central ATPase domain and flanking sequences that recruit auxiliary subunits. The catalytic subunits of SWI/SNF remodelers recruit Arp7/9 through a helicase/SANT-associated (HSA) domain N-terminal to the ATPase domain. Arp7/9-containing remodelers also carry the auxiliary subunit Rtt102, but the role of this subunit is poorly understood. Here, we show that Rtt102 binds with nanomolar affinity to the Arp7/9 heterodimer and modulates its conformation and interactions with the ATPase subunit and nucleotide. When bound to Rtt102, Arp7/9 interacts with a shorter segment of the HSA domain. Structural analysis by small-angle x-ray scattering further shows that when bound to Rtt102, the complex of Arp7/9 with the catalytic subunit assumes a more stable compact conformation. We also found that Arp7, Arp9, and Arp7/9 interact very weakly with ATP, but Rtt102 promotes high-affinity ATP binding to a single site in the heterodimer. Collectively, the results establish a function for subunit Rtt102 as a stabilizing factor for the Arp7/9 heterodimer, enhancing its interaction with nucleotide and controlling the conformation of SWI/SNF remodelers in an Arp7/9-dependent manner.
authors.affiliation: From the Department of Physiology and.
authors.forename: Bengi
authors.initials: B
authors.lastname: Turegun
authors.forename: David J
authors.initials: DJ
authors.lastname: Kast
authors.forename: Roberto
authors.initials: R
authors.lastname: Dominguez
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D020134:Catalytic Domain; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009707:Nucleosomes / Q000235:genetics*; D011485:Protein Binding; D017510:Protein Folding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism
chemical_list: C116139:ARP7 protein, S cerevisiae; C116140:ARP9 protein, S cerevisiae; D002352:Carrier Proteins; D002868:Chromosomal Proteins, Non-Histone; D009707:Nucleosomes; C586369:Rtt102 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000255:Adenosine Triphosphate
keywords: ATP; Actin; Actin-related Proteins; Chromatin Remodeling; Isothermal Titration Calorimetry; Nucleotide Binding; Protein-Protein interactions; X-ray Scattering