title: Histone Chaperone Nap1 Is a Major Regulator of Histone H2A-H2B Dynamics at the Inducible GAL Locus.
abstract: Histone chaperones, like nucleosome assembly protein 1 (Nap1), play a critical role in the maintenance of chromatin architecture. Here, we use the GAL locus in Saccharomyces cerevisiae to investigate the influence of Nap1 on chromatin structure and histone dynamics during distinct transcriptional states. When the GAL locus is not expressed, cells lacking Nap1 show an accumulation of histone H2A-H2B but not histone H3-H4 at this locus. Excess H2A-H2B interacts with the linker DNA between nucleosomes, and the interaction is independent of the inherent DNA-binding affinity of H2A-H2B for these particular sequences as measured in vitro When the GAL locus is transcribed, excess H2A-H2B is reversed, and levels of all chromatin-bound histones are depleted in cells lacking Nap1. We developed an in vivo system to measure histone exchange at the GAL locus and observed considerable variability in the rate of exchange across the locus in wild-type cells. We recapitulate this variability with in vitro nucleosome reconstitutions, which suggests a contribution of DNA sequence to histone dynamics. We also find that Nap1 is required for transcription-dependent H2A-H2B exchange. Altogether, these results indicate that Nap1 is essential for maintaining proper chromatin composition and modulating the exchange of H2A-H2B in vivo.
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Xu
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA Howard Hughes Medical Institute, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Sheena
authors.initials: S
authors.lastname: D'Arcy
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Radebaugh
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA Howard Hughes Medical Institute, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Krzizike
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Holli A
authors.initials: HA
authors.lastname: Giebler
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Liangquan
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Nyborg
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA Howard Hughes Medical Institute, Colorado State University, Fort Collins, Colorado, USA Institute for Genome Architecture and Function, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Karolin
authors.initials: K
authors.lastname: Luger
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA Institute for Genome Architecture and Function, Colorado State University, Fort Collins, Colorado, USA Laurie.Stargell@colostate.edu.
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Stargell
mesh_terms: D002843:Chromatin / Q000378:metabolism; D005686:Galactokinase / Q000235:genetics*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D056426:Genetic Loci; D006657:Histones / Q000378:metabolism*; D005810:Multigene Family; D056490:Nucleosome Assembly Protein 1 / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; C518355:GAL10 protein, S cerevisiae; D006657:Histones; C493530:Htz1 protein, S cerevisiae; C533556:NAP1 protein, S cerevisiae; D056490:Nucleosome Assembly Protein 1; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; C524219:GAL1 protein, S cerevisiae; D005686:Galactokinase