Condensin II Regulates Interphase Chromatin Organization Through the Mrg-Binding Motif of Cap-H2.

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.
Mesh Terms:
Adenosine Triphosphatases, Amino Acid Motifs, Animals, Cell Line, Cells, Cultured, Chromatin, Chromosomal Proteins, Non-Histone, DNA-Binding Proteins, Drosophila, Drosophila Proteins, Gene Expression, Genes, Reporter, Genome, Interphase, Multiprotein Complexes, Mutation, Polytene Chromosomes, Protein Binding, Protein Interaction Domains and Motifs, Protein Transport, Transcription, Genetic, Transcriptional Activation
G3 (Bethesda)
Date: Mar. 09, 2015
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