Heterologous expression of human H1 histones in yeast

The complete set of seven human H1 histone subtype genes was heterologously expressed in yeast. Since Saccharomyces cerevisiae lacks standard histone H1 we could isolate each recombinantly expressed human H1 subtype in pure form without contamination by endogenous H I histones. For isolation of the H1 histones in this expression system no tagging was needed and the isoforms could be extracted with the authentic primary structure by a single extraction step with 5%(0.74 M) perchloric acid. The isolated H1 histone proteins were used to assign the subtype genes to the corresponding protein spots or peaks after two-dimensional gel electrophoresis and capillary zone electrophoresis, respectively. This allowed us to correlate transcriptional data with protein data, which was barely possible until now.