HISTONE H1 IN SACCHAROMYCES-CEREVISIAE

The existence of histone H1 in the yeast, Saccharomyces cerevisiae, ha s long been debated. In this report we describe the presence of histon e HI in yeast. YPL127c, a gene encoding a protein with a high degree o f similarity to histone H1 from other species was sequenced as part of the contribution of the Montreal Yeast Genome Sequencing Group to chr omosome XVI. To reflect this similarity, the gene designation has been changed to HHO1 (Histone H One). The HHO1 gene is highly expressed as poly A(+) RNA in yeast. Although deletion of this gene had no detecta ble effect on cell growth, viability or mating, it significantly alter ed the expression of beta-galactosidase from a CYCl-lacZ reporter. Flu orescence observed in cells expressing a histone H1-GFP protein fusion indicated that histone HI is localized to the nucleus.