Amy Zhang L&S Sciences
Investigating the role of the SIR complex in heterochromatin formation in yeast
The precise regulation of gene expression programs is fundamental for all cellular processes. The control of gene expression involving transcriptional activation and/or transcriptional repression is achieved by highly specific protein complexes. The aim of my work is to understand the mechanistic details of the yeast transcription repressor, the SIR complex, which is made up of three proteins: Sir2, Sir3, and Sir4. The SIR complex is critical for the epigenetic regulation of gene expression and the maintenance of chromosome stability. The comparative analysis of the different mechanisms of transcription repression processes between humans and S. cerevisiae will give a better understanding of how deregulation of SIR proteins and their conserved human homologs (Sirtuins) play a role in diseases such as diabetes and Alzeheimers. Specifically, since the mechanism of recruitment of SIR complex to specific genes has not yet been determined, I will investigate the mechanisms involved in the formation of the heterochromatin using cryo-electron microscopy to image the SIR-nucleosome interactions.