Sir2 protein mainly causes:
Sir2 founding member of sirtuin family is NAD-dependent class III histone deacetylase central to mating type and telomere silencing in Saccharomyces cerevisiae. Sir2 catalyzes deacetylation of acetyl-lysine producing deacetylated histone, nicotinamide, O-acetyl-ADP-ribose using NAD as co-substrate. Preferred substrates H4K16ac, H3K9ac, H3K14ac removal creates hypoacetylated nucleosomes high-affinity for Sir3 bromo adjacent homology domain and Sir4 binding, enabling spreading of SIR complex. Fission yeast Sir2 similarly deacetylates H3K9ac facilitating Clr4 methylation. Sir2 also deacetylates n
Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 4: Sir2 Histone Deacetylation and Heterochromatin Spreading
