Resveratrol, a small molecule found in red wine, is reported to slow aging in simple eukaryotes and has been suggested as a potential calorie restriction mimetic. Resveratrol has also been reported to act as a sirtuin activator, and this property has been proposed to account for its anti-aging effects. We show here that resveratrol is a substrate-specific activator of yeast Sir2 and human SirT1. In particular, we observed that, in vitro, resveratrol enhances binding and deacetylation of peptide substrates that contain Fluor de Lys, a non-physiological fluorescent moiety, but has no effect on binding and deacetylation of acetylated peptides lacking the fluorophore. Consistent with these biochemical data we found that in three different yeast strain backgrounds, resveratrol has no detectable effect on Sir2 activity in vivo, as measured by rDNA recombination, transcriptional silencing near telomeres, and life span. In light of these findings, the mechanism accounting for putative longevity effects of resveratrol should be reexamined.

The active site in AcpS is only formed when two AcpS molecules dimerize. The addition of a third molecule allows for the formation of two additional active sites and also permits a large hydrophobic surface from each molecule of AcpS to be buried in the trimer. The mutations Ile5-->Arg, Gln113-->Glu and Gln113-->Arg show that AcpS is inactive when unable to form a trimer. The co-crystal structures of AcpS-CoA and AcpS-ACP allow us to propose a catalytic mechanism for this class of 4'-phosphopantetheinyl transferases.

High-throughput screening against the human sirtuin SIRT1 led to the discovery of a series of indoles as potent inhibitors that are selective for SIRT1 over other deacetylases and NAD-processing enzymes. The most potent compounds described herein inhibit SIRT1 with IC50 values of 60-100 nM, representing a 500-fold improvement over previously reported SIRT inhibitors. Preparation of enantiomerically pure indole derivatives allowed for their characterization in vitro and in vivo. Kinetic analyses suggest that these inhibitors bind after the release of nicotinamide from the enzyme and prevent the release of deacetylated peptide and O-acetyl-ADP-ribose, the products of enzyme-catalyzed deacetylation. These SIRT1 inhibitors are low molecular weight, cell-permeable, orally bioavailable, and metabolically stable. These compounds provide chemical tools to study the biology of SIRT1 and to explore therapeutic uses for SIRT1 inhibitors.

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Structural data were collected for both the apo and holo forms of ACP that suggest that the two forms of ACP are essentially identical. Comparison of the published structures for E. coli ACP and actinorhodin polyketide synthase acyl carrier protein (act apo-ACP) from Streptomyces coelicolor A3(2) with B. subtilis ACP indicates similar secondary structure elements but an extremely large rmsd between the three ACP structures (>4.3 A). The structural difference between B. subtilis ACP and both E. coli and act apo-ACP is not attributed to an inherent difference in the proteins, but is probably a result of a limitation in the methodology available for the analysis for E. coli and act apo-ACP. Comparison of the structure of free ACP with the bound form of ACP in the ACP-ACPS complex reveals a displacement of helix II in the vicinity of Ser36. The induced perturbation of ACP by ACPS positions Ser36 proximal to coenzyme A and aligns the dipole of helix II to initiate transfer of 4'-PP to ACP.