UMMS Affiliation

Program in Molecular Medicine

Publication Date


Document Type



Alleles; Animals; Chromatin; DNA, Fungal; DNA-Binding Proteins; *Gene Silencing; Histones; Models, Molecular; Nucleic Acid Conformation; Nucleosomes; Protein Structure, Tertiary; Recombinant Proteins; Saccharomyces cerevisiae; *Transcription, Genetic; Xenopus Proteins; Xenopus laevis


Life Sciences | Medicine and Health Sciences


Genetic experiments have identified two structurally similar nucleosomal domains, SIN and LRS, required for transcriptional repression at genes regulated by the SWI/SNF chromatin remodeling complex or for heterochromatic gene silencing, respectively. Each of these domains consists of histone H3 and H4 L1 and L2 loops that form a DNA-binding surface at either superhelical location (SHL) +/-2.5 (LRS) or SHL +/-0.5 (SIN). Here we show that alterations in the LRS domain do not result in Sin(-) phenotypes, nor does disruption of the SIN domain lead to loss of ribosomal DNA heterochromatic gene silencing (Lrs(-) phenotype). Furthermore, whereas disruption of the SIN domain eliminates intramolecular folding of nucleosomal arrays in vitro, alterations in the LRS domain have no effect on chromatin folding in vitro. In contrast to these dissimilarities, we find that the SIN and LRS domains are both required for recruitment of Sir2p and Sir4p to telomeric and silent mating type loci, suggesting that both surfaces can contribute to heterochromatin formation. Our study shows that structurally similar nucleosomal surfaces provide distinct functionalities in vivo and in vitro.

DOI of Published Version



Mol Cell Biol. 2006 Dec;26(23):9045-59. Epub 2006 Oct 2. Link to article on publisher's site

Journal/Book/Conference Title

Molecular and cellular biology

Related Resources

Link to Article in PubMed

PubMed ID