Abstracts
The Enzymatic Activity of Sirtuins: Beyond NAD-Dependent Deacetylation
Hening Lin, Cornell University
Sirtuins have been recognized as NAD-dependent deacetylases that regulate important biological processes, including life span, transcription, cell survival, and metabolism. Mammals have 7 sirtuins, SIRT1-7. Of the seven human sirtuins, only three of them, SIRT1, SIRT2, and SIRT3, have robust deacetylation activities in vitro and in vivo. The other sirtuins either have no detectable or very weak deacetylation activity in vitro. I will present our work demonstrating that sirtuins with no or very weak deacetylation activity have other enzymatic activities that may regulate transcription and other biological processes.
Sirtuins, NAD and Dietary Restriction Combine to Modulate Epigenetic States, Gene Expression and Protein Activity
Anthony Sauve, Weill Cornell Medical College
Sirtuins are biologically conserved protein deacetylases that react NAD with histones and other proteins, such as transcription factors and enzymes, thus regulating diverse biological processes. Sirtuin enzymes are highly responsive to changes induced by dietary restriction and appear to mediate a number of potent biological effects attributed to reduced calorie intake, such as increased lifespan. This seminar will explore how nature uses the highly conserved catalytic site of sirtuins to accomplish lysine deacetylation. In addition, studies to determine how sirtuin activities are linked to dietary restriction will be examined.
Molecular Recognition of the Nucleosome
Song Tan, Penn State University
Although we have a reasonable understanding of how proteins bind to DNA, we lack an equivalent understanding of how chromatin enzymes and factors interact with chromatin. My laboratory is investigating how the chromatin factor RCC1 (regulator of chromosomal condensation) interacts with the nucleosome to regulate mitosis, nucleocytoplasmic transport and nuclear envelope dynamics. Our biochemical studies and our crystal structure of the 300 kD RCC1/nucleosome core particle complex show us for the first time the molecular details of how a chromatin factor recognizes the nucleosome.