EXAMINING THE ROLE OF THE SANT DOMAIN IN BINDING OF LSD1-COREST TO THE H4 TAIL OF THE NUCLEOSOME

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Author:
Spadafora, Victoria K
Area of Honors:
Biochemistry and Molecular Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Song Tan, Thesis Supervisor
  • Ming Tien, Honors Advisor
Keywords:
  • LSD1/CoREST
  • Nucleosome
  • Histone
  • Gene Regulation
Abstract:
LSD1, a lysine specific demethylase enzyme, requires a corepressor, CoREST, to demethylate nucleosome substrates. LSD1-CoREST’s demethylase activity provides its gene regulation abilities through transcriptional activation and suppression. Active genes are characterized by methylated lysine four in histone H3 and silenced genes by methylated lysine nine on histone H3. A preliminary low resolution structure of LSD1- CoREST in complex with the nucleosome has been solved in our lab, but further experiments are needed to determine all points of interaction between the two components. The SANT domain is a region of CoREST that is conserved among corepressors and has proven to have a role in chromatin remodeling through histone modifications. Our lab’s preliminary structure suggests a potential interaction between the SANT domain of CoREST and the histone H4 tail of the nucleosome. Mutations to the SANT domain could potentially interfere with this interaction, hindering LSD1-CoREST’s ability to bind to the nucleosome. I made mutations in the SANT domain, converting amino acids in the acidic patch to the neutral alanine, which could disrupt their ability to interact with the basic H4 tail. Nucleosome binding assays were performed to assess the change in binding affinity of the demethylase and corepressor complex to the nucleosome. Determining the presence and essentiality of aforementioned interactions is important for refining the model of and mechanism through which LSD1-CoREST and the nucleosome interact. It can also help determine target areas for disrupting or enhancing the binding of this complex. LSD1-CoREST’s oncogenic properties make these targets a point of interest for therapeutic treatment for cancer.