Condensin II regulates interphase chromatin organization through the Mrg-binding motif of Cap-H2

Heather A. Wallace, Joseph E. Klebba, Thomas Kusch, Gregory C. Rogers, Giovanni Bosco

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)803-817
Number of pages15
JournalG3: Genes, Genomes, Genetics
Volume5
Issue number5
DOIs
StatePublished - 2015

Keywords

  • Chromatin organization
  • Chromosome structure
  • Condensin
  • Homolog pairing
  • Mrg15

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Genetics(clinical)

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