Work in my laboratory focuses on the study of glycogen metabolism and its regulation. Glycogen is a branched polymer of glucose that functions as a store of both energy and carbon skeletons in many species ranging from mammals to bacteria. We have a longstanding interest in understanding the control of glycogen storage in the budding yeast, Saccharomyces cerevisiae. More recently, we have entered into collaboration with Dr. Andrew Brittingham from the Department of Microbiology and Immunology and expanded our work to consideration of the role of glycogen in a variety of protists of medical interest. Our current projects are outlined below.
A. The role of glycogen stores in the protists Trichomonas vaginalis and Giardia intestinalis.
T. vaginalis and G. intestinalis are both obligate parasites of significant medical importance in man. T. vaginalis is the causative agent of trichomoniasis, the most common non-viral sexually transmitted disease worldwide whereas G. intestinalis infection is an important cause of diarrheal illness. Both organisms have been shown to accumulate substantial quantities of glycogen at particular points during growth. Our current work addresses the kinetics of glycogen synthesis and utilization as well as the properties of the enzymes responsible for these processes. With T. vaginalis, we have determined that two isoforms of glycogen phosphorylase are expressed constitutively and that, unlike many eukaryotic glycogen phosphorylases, these enzymes are not regulated by reversible protein phosphorylation. We have also begun characterization of the T. vaginalis glycogen synthase. With G. intestinalis, we obtained evidence suggesting that the accumulation of glycogen may be an intermediary step in the generation of spore-wall carbohydrate and thus plays a key role in the lifecycle of the protist.
B. Secreted glucosidases of Trichomonas vaginalis
We are interested in determining how T. vaginalis secures the nutrients required to successfully colonize the vagina and establish an infection. In particular, we have focused on how the organism is able to obtain a steady supply of carbohydrate, which it depends upon for growth. Human vaginal epithelial cells contain substantial quantities of glycogen and it has long been hypothesized that this glycogen, released upon cell lysis, may serve as a growth substrate for vaginal flora. Could T. vaginalis make use of this glycogen? We have established that T. vaginalis grows equally well in growth media containing either glycogen or glucose as a carbon source. Furthermore, we can detect secreted glucosidase activities in conditioned growth medium. Preliminary characterization indicates that at least an α-amylase is secreted. Current work is directed toward the further purification and characterization of the secreted glucosidases. We hope to identify the enzymes required by T. vaginalis for utilization of exogenous glycogen, ultimately perhaps leading to the identification of novel therapies for trichomoniasis.
Brittingham A and Wilson WA. The Antimicrobial Effect of Boric Acid on Trichomonas vaginalis. Sex Transm Dis. 41:718-722., 2014
Dirkx M, Boyer MP, Pradhan P, Brittingham A, and Wilson WA. Expression and characterization of a β-fructofuranosidase from the parasitic protist Trichomonas vaginalis. BMC Biochem. 15:12. doi: 10.1186/1471-2091-15-12., 2014
Nielsen TJ, Pradhan P, Brittingham A, and Wilson WA. Glycogen accumulation and degradation by the trichomonads Trichomonas vaginalis and Trichomonas tenax. J Eukaryot Microbiol. 59:359-366., 2012
Pradhan P, Lundgren SW, Wilson WA, and Brittingham A. Glycogen storage and degradation during in vitro growth and differentiation of Giardia intestinalis. J Parasitol. 98:442-444., 2012
Baskaran S, Chikwana VM, Contreras CJ, Davis KD, Wilson WA, DePaoli-Roach AA, Roach PJ, and Hurley TD. Multiple glycogen-binding sites in eukaryotic glycogen synthase are required for high catalytic efficiency toward glycogen. J Biol Chem. 286:33999-34006., 2011
Wilson W.A., Henry M.K., Ewing G., Rehmann J., Canby C.A., Gray J.T., Finnerty E.P. Teach Learn Med 23:256-262. “A prematriculation intervention to improve the adjustment of students to medical school”, 2011
Wilson, W.A., Boyer, M.P., Davis, K.D., Burke, M., and Roach P.J. Can J Microbiol. 56, 408-420. “The subcellular localization of yeast glycogen synthase is dependent upon glycogen content”, 2010
Wilson, W.A., Roach P.J., Montero M., Baroja-Fernández E., Muñoz F.J., Eydallin G., Viale A.M., and Pozueta-Romero J. FEMS Microbiol Rev. 34, 952-985. “Regulation of glycogen metabolism in yeast and bacteria”, 2010
Wilson, W.A., Skurat, A.V., Probst, B., de Paoli-Roach, A.A., Roach, P.J., and Rutter, J.A., Proc. Natl. Acad. Sci. USA 102, 16596-16601. “Control of mammalian glycogen synthase by PAS kinase”. , 2005
Torija M.J., Novo M., Lemassu A., Wilson W, Roach P.J., Francois J., and Parrou J.L., FEBS Lett. 579, 3999-4004. “Glycogen synthesis in the absence of glycogenin in the yeast Saccharomyces cerevisiae”. , 2005
de Paula R.M., Wilson W.A., Roach P.J., Terenzi H.F. and Bertolini M.C., FEBS Lett. 579, 2208-2214. “Biochemical characterization of Neurospora crassa glycogenin (GNN), the self-glucosylating initiator of glycogen synthesis”. , 2005
Wilson, W.A., Wang, Z., and Roach, P.J., Biochem. Biophys. Res. Commun. 329, 161-167. “Regulation of yeast glycogen phosphorylase by the cyclin-dependent protein kinase Pho85p” , 2005
de Paula R., Wilson, W.A., Terenzi, H.F., Roach, P.J., and Bertolini M.C., Arch. Biochem. Biophys. 435, 112–124. “GNN is a self-glucosylating protein involved in the initiation step of glycogen biosynthesis in Neurospora crassa”. , 2005
Wilson W.A., Hughes W.E., Tomamichel W. and Roach P.J., Biochem. Biophys. Res. Commun. 320, 416-423. “Increased glycogen storage in yeast results in less branched glycogen”. , 2004
Pederson, B.A., Wilson, W.A., and Roach, P.J., J. Biol. Chem. 279, 13764-13768. “Glycogen synthase sensitivity to glucose-6-P is important for controlling glycogen accumulation in Saccharomyces cerevisiae”. , 2004
Wilson, W.A., Wang, Z. and Roach, P.J., FEBS Lett. 515, 104-108. “Analysis of respiratory mutants reveals new aspects of the control of glycogen accumulation by the cyclin-dependent protein kinase Pho85p”. , 2002
Wilson, W.A., Wang, Z. and Roach, P.J., Mol. Cell Proteomics 1, 232-242. “Systematic identification of the genes affecting glycogen storage in the yeast Saccharomyces cerevisiae: implication of the vacuole as a determinant of glycogen level”. , 2002
Wang, Z., Wilson, W.A., Fujino, M.A. and Roach, P.J., FEBS Lett. 506, 277-280. “The yeast cyclins Pcl6p and Pcl7p are involved in the control of glycogen storage by the cyclin-dependent protein kinase Pho85p”. , 2001
Wang, Z., Wilson, W.A., Fujino, M.A. and Roach, P.J., Mol. Cell Biol. 21, 5742-5752. “Control of autophagy and glycogen accumulation by Snf1p, the yeast homolog of the AMP-activated protein kinase”. , 2001
Pederson, B.A., Cheng, C., Wilson, W.A. and Roach, P.J., J. Biol. Chem 275, 27753-27761. , 2000
Wilson, W.A., Mahrenholz, A.M. and Roach, P.J., Mol. Cell Biol. 19, 7020-7030. “Substrate targeting of the yeast cyclin-dependent kinase Pho85p by the cyclin Pcl10p”., 1999