p53 related chromatin and ubiquitylation pathways

Our research focuses on the structural and biochemical characterization of proteins involved in cancer pathways, especially that of the tumor suppressor, p53. The goals of our research are to understand how p53 and related proteins communicate and signal in complex processes such as DNA damage recognition and repair, transcription regulation, and ubiquitin-mediated degradation. We take a genome-wide approach, studying whole families of related proteins that may have an impact on these pathways in order to understand how proteins selectively interact with specific members of a sequence-related family. We use Nuclear Magnetic Resonance (NMR) Spectroscopy and x-ray crystallography in conjunction with other physical and biochemical techniques to study the three-dimensional (3D) structure, dynamics and biochemical properties of proteins, protein-DNA and proteinprotein complexes.

p53 is a central integrator of signaling pathways that guard genomic integrity, thereby preventing tumorigenesis. The cellular levels of p53 are tightly regulated by several ubiquitin E3 ligases that promote ubiquitylation and target p53 for 26S proteosome- dependent protein degradation. We are studying proteins that both add and remove ubiquitin from p53. We are also investigating other post-translational modifications of p53 (phosphorylation, methylation and acetylation), and how these modifications may act as signals by altering p53’s interactions with other proteins, DNA and/or chromatin. Other systems under study in the lab include the breast cancer susceptibility gene, BRCA1, the human ubiquitylation system, and proteins that “read” and “write” histone marks such as methyl- lysine recognizing proteins such as MBT repeat proteins, Chromodomains and methyl- and acetyl-transferases.

http://nmr.uhnres.utoronto.ca/arrowsmith
http://www.uhnres.utoronto.ca/proteomics

Graduate Students:

• Ryan Doherty
• Jack Liao
• Nataliya Nady
• Janet Wan (Co-supervised)

Selected References:

• Min J, Allali-Hassani A, Nady N, Qi C, Ouyang H, Liu Y, MacKenzie F, Vedadi M and Arrowsmith CH. L3MBTL1 recognition of mono- and dimethylated histones, Nature Struct. Mol. Biol. 14, 1229-30 (2007)

• Kaustov L, Lukin J, Lemak A, Duan S, Doherty R, Penn LZ, Arrowsmith CH.. The conserved CPH domains of Cul 7 and PARC are protein-protein interaction modules that bind the tetramerization domain of P53. J Biol Chem. 282, 11300-7 (2007).

• Sheng Y, Saridakis V. Sarkari F, Duan S, Wu T, Arrowsmith CH, and Frappier L. Molecular recognition of p53 and MDM2 by USP7/HAUSP, Nat Struct Mol Biol, 13, 285-91. (2006).