Effects on the promoter nucleosomes on expression levels and expression noise. (A) No correlation between promoter nucleosome properties and expression levels. NFR size and occupancy of +1 and −1 nucleosomes are plotted against gene expression values (top to bottom) for Open and Closed promoters separately. No correlation is observed with R2 < 0.04. (B) Correlations between transcription machinery binding and expression levels. In contrast to nucleosome properties, the transcription machinery binding correlates nicely with expression levels with R2 between 0.2 and 0.3. (C) Closed promoters tend to have noisier expression. Distributions of gene-expression noise for TATA-containing and TATA-less promoters in Open and Closed configurations. TATA-less promoters (top panel) show significantly lower noise than TATA-containing ones (bottom panel; compare box-plots joined by red lines). Among the latter, Closed promoters show even more noise than Open promoters. There is no difference in noise levels between the two architectures among TATA-less promoters. P-values were calculated using the Wilcoxon rank sum test.
