Department of Genetics, Institute of Molecular Biology, University
of Copenhagen, Øster Farimagsgade 2A, DK-1353 Copenhagen K, Denmark
1Present address: Active Biotech Research AB, Box 724,
SE-220 07 Lund, Sweden
2Corresponding author e-mail: gensteen@biobase.dk
The Saccharomyces cerevisiae NHP6A and NHP6B proteins are chromatin architectural factors, functionally and structurally related to the mammalian high mobility group (HMG)-1 and -2 proteins, a family of non-sequence-specific DNA binding proteins. nhp6a nhp6b mutants have various morphological defects and are defective in the induced expression of several RNA polymerase II-transcribed genes. We found that NHP6A/B proteins are also required for full induction of the yeast CHA1 gene. Importantly, CHA1 basal level expression is increased 10-fold in an nhp6a nhp6b double deletion mutant. Micrococcal nuclease and DNase I analysis of the CHA1 gene in this strain showed an open promoter structure, characteristic of the activated state of this promoter, even under non-inducing conditions. To address the possible function of the NHP6A/B proteins in chromatin-mediated gene regulation, we performed whole-genome transcriptional profiling of a delta nhp6a delta nhp6b yeast strain. Our results suggest that NHP6A/B proteins play an important regulatory role, repressing as well as potentiating expression of genes involved in several cellular processes, and that NHP6A/B control is exerted at the level of the individual gene.
1. "Metabolism and Morphology of Ribonucleoprotein Particles from the Cell Nucleus of Lymphocytes".
2. "Repressed and Active Chromatin Isolated from Interphase Lymphocytes".
3. "Nuclear Polyanions as De-Repressors of Synthesis of Ribonucleic Acid".
4. "Mechanisms of Repression and De-Repression within Interphase Chromatin".
5. "Nuclear Ribosomes and RNA-RNA Duplexes".