Modulators for Sirt5 and assays for screening same

1. A method for identifying a modulator of Sirt5 demalonylase or desuccinylase activity, comprising:

providing a candidate compound;

providing a substrate comprising a malonyl or succinyl lysine linked to an indicator moiety;

contacting the substrate with Sirt5 in the presence of the candidate compound and in the presence of nicotinamide adenine dinucleotide (NAD) under conditions for Sirt5 to demalonylate or desuccinylate the substrate;

contacting the demalonylated or desuccinylated substrate with a cleavage agent that cleaves the linkage between the lysine and the indicator moiety to release the indicator moiety, thereby generating a detectable signal; and

correlating signal intensity with Sirt5 demalonylase or desuccinylase activity;

wherein a change in Sirt5 demalonylase or desuccinylase activity in the presence of the candidate compound, relative to Sirt5 demalonylase or desuccinylase activity in the absence of the candidate compound, identifies the candidate compound as a modulator of Sirt5 demalonylase or desuccinylase activity.

2. The method of claim 1 , wherein the substrate is a peptide comprising a malonyl or succinyl lysine covalently linked to the indicator moiety through a peptide bond.

3. The method of claim 2 , wherein the cleavage agent is a proteolytic enzyme.

4. The method of claim 3 , wherein the proteolytic enzyme is trypsin.

5. The method of claim 1 , wherein the indicator moiety has fluorescent properties.

6. The method of claim 5 , wherein the indicator moiety comprises a fluorophore which changes its emission wavelength upon the cleavage and release of the indicator moiety.

7. The method of claim 5 , wherein the indicator moiety comprises a fluorophore and the substrate is also labeled with a quenching group, and upon cleavage from the substrate, the indicator moiety generates a fluorescent signal.

8. The method of claim 5 , wherein the indicator moiety comprises a fluorophore which is one member of a donor-acceptor fluorophore pair and is attached to the carboxyl terminus of the lysine residue, and the other member of the pair is attached directly or indirectly to the amino terminus of the lysine residue.

9. The method of claim 8 , wherein cleavage of the indicator fluorophore from the substrate reduces FRET-based signal intensity.

10. The method of claim 5 , wherein the indicator moiety is AMC.

11. The method of claim 10 , wherein the substrate is ISGASE(SuK)-AMC (SEQ ID NO: 11).

12. The method of claim 1 , wherein the candidate compound is a small molecule.

13. The method of claim 12 , wherein the candidate compound has the formula:

wherein:

R 1 is an anionic or ionizable group;

R 2 is selected from S, NR 5 , and O, wherein R 5 is H, methyl, ethyl, isopropyl, phenyl, or benzyl;

when R 1 is carboxyl, then R 2 is not O, and when R 2 is O, then R 1 is not carboxyl;

X 0 , X 1 , X 2 , X 3 , X 4 , X 5 , X 6 and X 7 are independently selected from —(CH 2 ) n —, wherein n represents 1, 2, or 3, —NR 5 —, —O—, —S—, or a bond, provided that at least one of X 0 -X 4 is not a bond, and at least one of X 5 -X 7 is not a bond;

R 3 and R 4 are independently selected from H, hydrocarbon (R), amino acid, dipeptide, tripeptide, oligopeptide, protein, nucleobase, nucleotide, dinucleotide, trinucleotide, oligonucleotide, monosaccharide, disaccharide, oligosaccharide, and protecting groups or a combination thereof or modified form thereof.

14. The method of claim 1 , further comprising testing the ability of the candidate molecule to affect deacetylation activity of any of Sirt 1, 2, or 3.

15. The method of claim 13 , wherein R 2 is S.