Distribution of high mobility group proteins 1/2,E and 14/17 and linker histones H1 and H5 on transcribed and non-transcribed regions of chicken erythrocyte chromatin

摘要

Quantitative analysis of distribution of chromosomal proteins on single copy DNA sequences has been further developed. Our approach consists of DNAprotein crosslinking within whole cells or isolated nuclei, specific Immunoaffinity isolation of crosslinked complexes via protein and Identification of crosslinked DNA by hybridisation with single-stranded DNA probes. The present study shows that transcribed chromatin of chicken embryonic erythrocyte β globin gene is characterized by about 1.5 – 2.5-fold higher density of HMG 14/17 and 2-fold lower density of H1 and H5 as compared with non-transcribed chromatin of ovalbumin and lysozyrne genes, whereas HMG 1/2,E proteins were equally distributed between DNA of both transcribed and non-transcribed genes. The depletlon of H1/H5 in β globin sequences was verified by the ‘protein image' hybridisation technique (1). The DNase I hypersensitive site located 5′ upstream from β globin gene is deficient in all the proteins assayed, what implies a drastic disruption in the nucleosomal array. Minor quantttative changes of protein pattern suggest transient local perturbation of the chromatin on transcription.