title: Condensin II Regulates Interphase Chromatin Organization Through the Mrg-Binding Motif of Cap-H2.
abstract: The spatial organization of the genome within the eukaryotic nucleus is a dynamic process that plays a central role in cellular processes such as gene expression, DNA replication, and chromosome segregation. Condensins are conserved multi-subunit protein complexes that contribute to chromosome organization by regulating chromosome compaction and homolog pairing. Previous work in our laboratory has shown that the Cap-H2 subunit of condensin II physically and genetically interacts with the Drosophila homolog of human MORF4-related gene on chromosome 15 (MRG15). Like Cap-H2, Mrg15 is required for interphase chromosome compaction and homolog pairing. However, the mechanism by which Mrg15 and Cap-H2 cooperate to maintain interphase chromatin organization remains unclear. Here, we show that Cap-H2 localizes to interband regions on polytene chromosomes and co-localizes with Mrg15 at regions of active transcription across the genome. We show that co-localization of Cap-H2 on polytene chromosomes is partially dependent on Mrg15. We have identified a binding motif within Cap-H2 that is essential for its interaction with Mrg15, and have found that mutation of this motif results in loss of localization of Cap-H2 on polytene chromosomes and results in partial suppression of Cap-H2-mediated compaction and homolog unpairing. Our data are consistent with a model in which Mrg15 acts as a loading factor to facilitate Cap-H2 binding to chromatin and mediate changes in chromatin organization.
authors.affiliation: Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755.
authors.forename: Heather A
authors.initials: HA
authors.lastname: Wallace
authors.affiliation: Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, Tucson, Arizona 85721.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Klebba
authors.affiliation: Somerset, New Jersey 08873.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kusch
authors.affiliation: Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, Tucson, Arizona 85721.
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Rogers
authors.affiliation: Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755 Giovanni.Bosco@Dartmouth.edu.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Bosco
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004330:Drosophila; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D017930:Genes, Reporter; D016678:Genome; D007399:Interphase / Q000235:genetics*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation; D059007:Polytene Chromosomes; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D021381:Protein Transport; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: C577064:Cap-H2 protein, Drosophila; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C555520:MRG15 protein, Drosophila; D046912:Multiprotein Complexes; C108312:condensin complexes; D000251:Adenosine Triphosphatases
keywords: Mrg15; chromatin organization; chromosome structure; condensin; homolog pairing