Crystal Structure of Quinone Reductase 2 in Complex with Resveratrol^,

Abstract

Resveratrol has been shown to have chemopreventive, cardioprotective, and antiaging properties. Here, we report that resveratrol is a potent inhibitor of quinone reductase 2 (QR2) activity in vitro with a dissociation constant of 35 nM and show that it specifically binds to the deep active-site cleft of QR2 using high-resolution structural analysis. All three resveratrol hydroxyl groups form hydrogen bonds with amino acids from QR2, anchoring a flat resveratrol molecule in parallel with the isoalloxazine ring of FAD. The unique active-site pocket in QR2 could potentially bind other natural polyphenols such as flavonoids, as proven by the high affinity exhibited by quercetin toward QR2. K562 cells with QR2 expression suppressed by RNAi showed similar properties as resveratrol-treated cells in their resistance to quinone toxicity. Furthermore, the QR2 knockdown K562 cells exhibit increased antioxidant and detoxification enzyme expression and reduced proliferation rates. These observations could imply that the chemopreventive and cardioprotective properties of resveratrol are possibly the results of QR2 activity inhibition, which in turn, upregulates the expression of cellular antioxidant enzymes and cellular resistance to oxidative stress.Resveratrol (trans-3,4′,5-trihydroxystilbene) is a phyto-polyphenol that occurs in grapes and a variety of medicinal plants. Because of its abundance in grapes, it is present in significant amount in grape products such as grape juice and wines, particularly red wine (1). The revealing of resveratrol as a cancer chemopreventive agent in 1997 (2) sparked extensive research on its chemopreventive properties (3). Resveratrol has been tested on a variety of cancers in animal model studies. As in the case of the 1997 study, Jang et al. (2) demonstrated in a mouse model that resveratrol is effective in prevention of DMBA-(dimethylbenzanthracene) and TPA-(tetradecanoylphorbol-13-acetate) induced skin cancer. Application of 1, 5, 10, or 25 µM of resveratrol with TPA twice a week for 18 weeks reduced the number of skin tumors per mouse by 68, 81, 76, or 98%, respectively, and the percentage of mice with tumors was lowered by 50, 63. 63, or 88%. In mouse models of colon cancer and small intestinal cancer, resveratrol prevents cancer formation with 100 and 70% efficacy, respectively (4, 5). † This work was supported in part by National Institute of Health Grant R21 CA104424. ‡ The atomic coordinates and structure factors (PDB code 1SG0) NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptResveratrol has been suggested to block the multistep process of carcinogenesis, namely, tumor initiation, promotion, and progression (3). Despite extensive investigation, no clear molecular basis for the actions of resveratrol has emerged. A variety of hypotheses have been proposed to explain its functions: antioxidant effects, proapoptotic effects, cell-cycle regulation, inhibition of protein kinases, regulation of NFκB and Iκ3, and modulation of estrogen effects (3, 6). ...

Pyrimidine biosynthesis links mitochondrial respiration to the p53 pathway

“…This recently identified pathway involves inhibition of the ubiquitin-independent degradation of p53 in 20S proteasomes through its binding to NQO1 or NQO2 (20,24,25). We found that dicoumarol, which is known to interfere with the NQO1 binding to p53, and resveratrol, a highly specific inhibitor of NQO2 (31), can mitigate the stabilization of p53 and the induction of p53-dependent reporter in response to treatment with myxothiazol or PALA. Similar to the drug inhibitors, the p53-inducing effect of myxothiazol was alleviated in the cells with NQO1 or NQO2 downregulated by specific shRNAs.…”

Recent Advances in the Study on Resveratrol

“…However, 50 μM resveratrol promoted fat mobilization in white adipocytes by repressing PPARγ in 3T3-L1 cells, 93) which is inconsistent with our finding that 5 μM resveratrol activates PPARα, β/δ, and γ in BAECs. 12,32) Other candidate targets of resveratrol such as quinone reductase 2 (QR2), 94) AMP-activated protein kinase (AMPK), 95) and PPARγ coactivator (PGC)-1α 96) have also been reported. Resveratrol inhibits purified QR2, with a dissociation constant of 35 nM 94) ; 10 μM resveratrol as well as apigenin stimulated AMPK in HepG2 hepatoma cells 95) ; and 50 μM resveratrol induced PGC-1α-responsive genes such as medium chain acylCoA dehydrogenase, cytochrome C, and estrogen receptorrelated receptor α in C2C12 cells infected with an adenovirus expressing PGC-1α.…”

Resveratrol and health – A comprehensive review of human clinical trials

“…Resveratrol further inhibits cyclooxygenases [19], and could therefore act through some of the same mechanisms as aspirin. An unbiased approach to select resveratrol-binding proteins revealed quinone reductase 2, which is inhibited by resveratrol, as one of the highest affinity targets, although the significance of this observation is not yet known [20]. Fully defining the targets of resveratrol that are biologically relevant is an enormous task, made more difficult by questions of whether effects are either direct or indirect, and often conflicting results in different systems.…”