Gaurav Behera

The nicotinamide adenine dinucleotide (NAD+)–dependent deacetylase SIRT1 plays a vital role in a wide range of biological functions including metabolism and the regulation of healthspan. Whole-body overexpression of SIRT1 in mice has been found to promote characteristics of calorie-restriction like a decrease in age-related disease incidence including diabetes and cancer. It has been known that activation of SIRT1 is strongly dependent on structural features of the target substrate. While studies have demonstrated that various dietary small molecules can modulate SIRT1 activity allosterically, knowledge on how endogenous metabolites, other than cofactor NAD+, activate SIRT1 remains elusive. Preliminary data from our laboratory have shown that monounsaturated fatty acids (MUFAs) can increase SIRT1 activation when using acetylated FOXO3a as a substrate. Our objective is to determine the properties of SIRT1 targeting. We hypothesize that SIRT1 targets specific substrate peptide sequences. We aim to develop a pipeline to test our hypothesis by generating peptide libraries using an isokinetic coupling strategy that incorporates random amino acids at three amino acid residues in FOXO3a peptides up and downstream of the acetylated lysine to find the amino acid preference at each position. Identified substrate sequences will be input into positional matrixes allowing for the development of SIRT1 specific substrates. Our preliminary findings show that acidic residues downstream of the acetylated lysine are critical for SIRT1 targeting and SIRT1 activation is sensitive to hydrophobic residues at specific positions of the target peptide.