A human homologue of yeast anti-silencing factor has histone chaperone activity
Version of Record online: 25 DEC 2001
Genes to Cells
Volume 5, Issue 3, pages 221–233, March 2000
How to Cite
Munakata, T., Adachi, N., Yokoyama, N., Kuzuhara, T. and Horikoshi, M. (2000), A human homologue of yeast anti-silencing factor has histone chaperone activity. Genes to Cells, 5: 221–233. doi: 10.1046/j.1365-2443.2000.00319.x
- Issue online: 25 DEC 2001
- Version of Record online: 25 DEC 2001
Structural changes in chromatin play essential roles in regulating eukaryotic gene expression. Silencing, potent repression of transcription in Saccharomyces cerevisiae, occurs near telomeres and at the silent mating-type loci, as well as at rDNA loci. This type of repression relates to the condensation of chromatin that occurs in the heterochromatin of multicellular organisms. Anti-silencing is a reaction by which silenced loci are de-repressed. Genetic studies revealed that several factors participate in the anti-silencing reaction. However, actions of factors and molecular mechanisms underlying anti-silencing remain unknown.
Here we report the functional activity of a highly evolutionarily conserved human factor termed CIA (CCG1-interacting factor A), whose budding yeast homologue ASF1 has anti-silencing activity. Using yeast two-hybrid screening, we isolated histone H3 as an interacting factor of CIA. We also showed that CIA binds to histones H3/H4 in vitro, and that the interacting region of histone H3 is located in the C-terminal helices. Considering the functional role of CIA as a histone-interacting protein, we found that CIA forms a nucleosome-like structure with DNA and histones.
These results show that human CIA, whose yeast homologue ASF1 is an anti-silencing factor, possesses histone chaperone activity. This leads to a better understanding of the relationship between chromatin structural changes and anti-silencing processes.