TY - JOUR
T1 - A nonhistone protein-protein interaction required for assembly of the SIR complex and silent chromatin
AU - Rudner, Adam D.
AU - Hall, Brian E.
AU - Ellenberger, Tom
AU - Moazed, Danesh
PY - 2005/6
Y1 - 2005/6
N2 - Budding yeast silent chromatin, or heterochromatin, is composed of histones and the Sir2, Sir3, and Sir4 proteins. Their assembly into silent chromatin is believed to require the deacetylation of histones by the NAD-dependent deacetylase Sir1 and the subsequent interaction of Sir3 and Sir4 with these hypoacetylated regions of chromatin. Here we explore the role of interactions among the Sir proteins in the assembly of the SIR complex and the formation of silent chromatin. We show that significant fractions of Sir2, Sir3, and Sir4 are associated together in a stable complex. When the assembly of Sir3 into this complex is disrupted by a specific mutation on the surface of the C-terminal coiled-coil domain of Sir4, Sir3 is no longer recruited to chromatin and silencing is disrupted. Because in sir4 mutant cells the association of Sir3 with chromatin is greatly reduced despite the partial Sir2-dependent deacetylation of histones near silencers, we conclude that histone deacetylation is not sufficient for the full recruitment of silencing proteins to chromatin and that Sir-Sir interactions are essential for the assembly of heterochromatin.
AB - Budding yeast silent chromatin, or heterochromatin, is composed of histones and the Sir2, Sir3, and Sir4 proteins. Their assembly into silent chromatin is believed to require the deacetylation of histones by the NAD-dependent deacetylase Sir1 and the subsequent interaction of Sir3 and Sir4 with these hypoacetylated regions of chromatin. Here we explore the role of interactions among the Sir proteins in the assembly of the SIR complex and the formation of silent chromatin. We show that significant fractions of Sir2, Sir3, and Sir4 are associated together in a stable complex. When the assembly of Sir3 into this complex is disrupted by a specific mutation on the surface of the C-terminal coiled-coil domain of Sir4, Sir3 is no longer recruited to chromatin and silencing is disrupted. Because in sir4 mutant cells the association of Sir3 with chromatin is greatly reduced despite the partial Sir2-dependent deacetylation of histones near silencers, we conclude that histone deacetylation is not sufficient for the full recruitment of silencing proteins to chromatin and that Sir-Sir interactions are essential for the assembly of heterochromatin.
UR - http://www.scopus.com/inward/record.url?scp=18944384374&partnerID=8YFLogxK
U2 - 10.1128/MCB.25.11.4514-4528.2005
DO - 10.1128/MCB.25.11.4514-4528.2005
M3 - Article
C2 - 15899856
AN - SCOPUS:18944384374
VL - 25
SP - 4514
EP - 4528
JO - Molecular and Cellular Biology
JF - Molecular and Cellular Biology
SN - 0270-7306
IS - 11
ER -