3te6

From Proteopedia

Crystal Structure of the S. cerevisiae Sir3 AAA+ domain

Structural highlights

3te6 is a 2 chain structure with sequence from Saccharomyces cerevisiae S288C. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.8001Å
Ligands:
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

SIR3_YEAST The proteins SIR1 through SIR4 are required for transcriptional repression of the silent mating type loci, HML and HMR. The proteins SIR2 through SIR4 repress mulitple loci by modulating chromatin structure. Involves the compaction of chromatin fiber into a more condensed form.

Publication Abstract from PubMed

The silent information regulator 2/3/4 (Sir2/3/4) complex is required for gene silencing at the silent mating-type loci and at telomeres in Saccharomyces cerevisiae. Sir3 is closely related to the origin recognition complex 1 subunit and consists of an N-terminal bromo-adjacent homology (BAH) domain and a C-terminal AAA(+) ATPase-like domain. Here, through a combination of structure biology and exhaustive mutagenesis, we identified unusual, silencing-specific features of the AAA(+) domain of Sir3. Structural analysis of the putative nucleotide-binding pocket in this domain reveals a shallow groove that would preclude nucleotide binding. Mutation of this site has little effect on Sir3 function in vivo. In contrast, several surface regions are shown to be necessary for the Sir3 silencing function. Interestingly, the Sir3 AAA(+) domain is shown here to bind chromatin in vitro in a manner sensitive to histone H3K79 methylation. Moreover, an exposed loop on the surface of this Sir3 domain is found to interact with Sir4. In summary, the unique folding of this conserved Sir3 AAA(+) domain generates novel surface regions that mediate Sir3-Sir4 and Sir3-nucleosome interactions, both being required for the proper assembly of heterochromatin in living cells.

Structural basis for the role of the Sir3 AAA+ domain in silencing: interaction with Sir4 and unmethylated histone H3K79.,Ehrentraut S, Hassler M, Oppikofer M, Kueng S, Weber JM, Mueller JW, Gasser SM, Ladurner AG, Ehrenhofer-Murray AE Genes Dev. 2011 Sep 1;25(17):1835-46. PMID:21896656^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Ehrentraut S, Hassler M, Oppikofer M, Kueng S, Weber JM, Mueller JW, Gasser SM, Ladurner AG, Ehrenhofer-Murray AE. Structural basis for the role of the Sir3 AAA+ domain in silencing: interaction with Sir4 and unmethylated histone H3K79. Genes Dev. 2011 Sep 1;25(17):1835-46. PMID:21896656 doi:10.1101/gad.17175111