Biochemistry Seminar: Karim-Jean Armache, NYU Langone Med Center
Wed, Apr 30
12:00 PM — 1:00 PM
MarshakCity College of New York160 Convent Ave
Marshak, MR 1027
Karim-Jean Armache, NYU LMC, will give a talk on "Structural characterization of silent chromatin"Karim-Jean Armache, Asst. Prof. of Dept of Biochemistry & Molecular Pharmacology, NYU Langone Medical Center, will give a talk on "Structural characterization of silent chromatin"
Gene silencing is essential for regulating cell fate in eukaryotes. It has been shown that gene silencing factors can specifically bind and organize nucleosomes to form higher-order, compacted chromatin structures and that binding of these factors is regulated by posttranslational modifications of histone tails. I will discuss our structural and biochemical studies of silencing complexes, one example being a structure formed by the silencing domain of Sir3 on a nucleosome. The ‘silent information regulator’ (SIR) complex mediates heterochromatin formation at the mating type loci and telomeres in budding yeast. The crystal structure of the Sir3 BAH domain bound to a nucleosome core particle shows an extensive correlation between molecular contacts and mutations that were shown by genetic screens to impact silencing. Moreover the structure explains how covalent modifications on histone H4 lysine 16 (H4K16) and histone H3 lysine 79 (H3K79) regulate formation of a silencing complex that contains the nucleosome as a central component. Our data provide the visualization of a structure that silences genes important to determine cell fate, a hallmark issue in epigenetics.