| Autor: |
Mathieu, Martine, Nikolaev, Igor, Scazzocchio, Claudio, Felenbok, Béatrice |
| Předmět: |
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| Zdroj: |
Molecular Microbiology; Apr2005, Vol. 56 Issue 2, p535-548, 14p |
| Abstrakt: |
We have studied the chromatin organization of three promoters of thealcregulon ofAspergillus nidulans. No positioned nucleosomes are seen in thealdA(aldehyde dehydrogenase) promoter under any physiological condition tested by us. In thealcA(alcohol dehydrogenase I) andalcR(coding for the pathway-specific transcription factor) promoters, a pattern of positioned nucleosomes is seen under non-induced and non-induced repressed conditions. While each of these promoters shows a specific pattern of chromatin restructuring, in both cases induction results in loss of nucleosome positioning. Glucose repression in the presence of inducer results in a specific pattern of partial positioning in thealcAandalcRpromoters. Loss of nucleosome positioning depends absolutely on the AlcR protein and it is very unlikely to be a passive result of the induction of transcription. In analcRloss-of-function background and in strains carrying mutations of the respective AlcR binding sites of thealcAandalcRpromoters, nucleosomes are fully positioned under all growth conditions. Analysis of mutant AlcR proteins establishes that all domains needed for transcriptional activation and chromatin restructuring are included within the first 241 residues. The results suggest a two-step process, one step resulting in chromatin restructuring, a second one in transcriptional activation. Partial positioning upon glucose repression shows a specific pattern that depends on the CreA global repressor. AnalcRloss-of-function mutation is epistatic to acreAloss-of-function mutation, showing that AlcR does not act by negating a nucleosome positioning activity of CreA. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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