Analysis of histones from the yeast Saccharomyces carlsbergensis

Basic chromosomal proteins were isolated from the chromatin of the yeast Saccharomyces carlsbergensis by extraction with H2SO4 and were purified by ion-exchange chromatography. Electrophoresis of the purified fraction on acetic acid/urea gels revealed the presence of four main components. These four proteins were identified as histones H2A, H2B, H3 and H4 on the basis of their amino acid composition, molecular weight and solubility properties, all of which are very similar to the corresponding properties of the various histone proteins from other eukaryotic organisms. A fifth basic protein could be isolated from yeast chromatin by extraction with HClO4. The available evidence indicates this protein to be an H1-type histone. Yeast thus appears to contain a complete set of histone proteins which are strongly homologous to the histones occurring in higher eukaryotes.