One molecule of a linker histone such as histone H1 is incorporated into every metazoan nucleosome . Histone H1 has three distinct structural domains: the positively charged amino-terminal and carboxy-terminal tails are separated by a globular domain that is similar to the winged-helix motif found in sequence-specific DNA-binding proteins . The globular domain interacts with DNA immediately contiguous to that wrapped around the core histones [3,4], whereas the tail domains are important for the compaction of nucleosomal arrays . Experiments in vivo indicate that histone H1 does not function as a global transcriptional repressor, but instead has more specific regulatory roles [6-9]. In Xenopus, maternal stores of the B4 linker histone that are assembled into chromatin during the early cleavage divisions are replaced by somatic histone H1 during gastrulation . This transition in chromatin composition causes the repression of genes encoding oocyte-type 5S rRNAs, and restricts the competence of ectodermal cells to differentiate into mesoderm [6,9-11]. Here, we demonstrate that the globular domain of histone H1 is sufficient for directing gene-specific transcriptional repression and for restricting the mesodermal competence of embryonic ectoderm. We discuss our results in the context of specific structural roles for this domain in the nucleosome.
|Number of pages||4|
|Publication status||Published - 23 Apr 1998|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Agricultural and Biological Sciences(all)