Comparison on the structure and transcriptional capability of growing phase and stationary yeast chromatin: a model for reversible gene activation.

We have compared the structure of intra-nuclear and isolated chromatin from logarithmically growing yeast cells to chromatin from cells which had entered the stationary phase and ceased growing. Both chromatins show a similar nucleosomal repeat pattern, 160 bp repeat size, with staphylococcal nuclease and similar variability in repeat sizes within the genome. DNase I produces the same ladder (less than 120 b) and a quite similar extended ladder (120-300 b) which shows that both chromatins have phased nucleosomes. However, the rate of DNase I digestion of growing phase is greater than in stationary. Functionally speaking, growing phase nuclei are 5-20 times as active in the rate of endogenous transcription (all three polymerases are involved). The transcriptional and DNase I susceptibility differences noted in nuclei are maintained in sucrose gradient isolated oligonucleosomes and mononucleosomes from the two states.