Silent information regulator protein complexes in Saccharomyces cerevisiae: A SIR2/SIR4 complex and evidence for a regulatory domain in SIR4 that inhibits its interaction with SIR3

摘要

The SIR2, SIR3, and SIR4 silent information regulator proteins are involved in the assembly of silent chromatin domains in the budding yeast Saccharomyces cer- evisiae. Using a series of biochemical experiments, we have studied protein-protein interactions involving these proteins. We found that yeast extracts contained a SIR2/SIR4 complex that was associated with little or no SIR3. However, trunca- tions of the N-terminal two-thirds of the SIR4 protein allowed it to efficiently associate with SIR3, suggesting that the N-terminal domain of SIR4 inhibited its interaction with SIR3.