B213 Chemical and Life Sciences Laboratory
601 S. Goodwin Ave.
Urbana, IL 61801
Office: (217) 333-4139
Mail to: B213 CLSL, MC-110
601 S. Goodwin Ave.
Urbana, IL 61801
Peter A B Orlean
Professor of Microbiology
Enzymology, Glycobiology, Membrane Biology, Microbial Physiology
B.Sc. (Bacteriology), University of Newcastle-upon-Tyne, 1977
M.Phil. (Biochemistry), University of Cambridge, 1978
Ph.D. (Biochemistry), University of Cambridge, 1982
Post-Doctoral (Cell Biology), Universität Regensburg, 1983-1985
Post-Doctoral (Molecular Biology), Massachusetts Institute of Technology, 1985-1990
Mechanism of polysaccharide synthesis
Chitin and cellulose, which are beta-1,4-linked polymers of N-acetylglucosamine (GlcNAc) and glucose, respectively, are the planet’s two most abundant biopolymers. Chitin is a key structural component of fungal cell walls and the exoskeletons of insects and crustacea. The biological importance of chitin and the possibility of targeting chitin synthases with antifungal drugs and insecticides motivate us to understand the mechanism of chitin synthesis. Because chitin synthases are in the same enzyme family as cellulose synthases - Glycosyltransferase Family 2 – chitin synthases are also good models for studying the mechanism of synthesis of other beta-1,4-linked polysaccharides.
Chitin synthases are multispanning membrane proteins with a cytoplasmic domain that catalyzes transfer of GlcNAc from the sugar nucleotide donor UDP-GlcNAc to extend chitin chains, which are believed to be extruded concommitantly through the plasma membrane. We are using a combination of biochemistry, chemical biology, and genetics to explore the biochemistry of chitin biosynthesis. Key tools in our studies are i) a yeast strain in which an overexpressed chitin synthase is the sole detectable chitin synthase activity, which allows us to study a single synthase in isolation, and ii) procedures to isolate chitin oligosaccharides, which allow us to analyze reaction products in detail.
In our recent study, a collaboration with N.P. Price and A.V. Demchenko, we applied chemical biology and mass spectrometry to show that show that the free monomer, GlcNAc, as well as its analogues N-propanoyl-, and N-butanoyl-, and N-glycolylglucosamine, all prime formation of oligosaccharides by yeast chitin synthase 2. This is the first demonstration that a eukaryotic chitin synthase can use a low molecular weight primer. Moreover, the work is also the first direct evidence that beta-1,4-linked polysaccharide synthases can add monomers one sugar at a time, because disaccharides were major reaction products.
We are now addressing the following questions about the synthesis of beta-1,4-linked polysaccharides. How is polymerization initiated de novo? What governs chitin chain length? Do different chitin synthases make different chain length distributions, and what are the consequences of such differences in vivo? Can chitin synthases use the UDP derivatives of GlcNAc analogues as substrates and generate chitin derivatives with novel properties?
American Cancer Society Junior Faculty Research Award, 1993-1996
Helen Corley Petit Professorship, UIUC College of Liberal Arts and Sciences, 1997-1998
University Scholar, University of Illinois, Urbana, 1997-1998
Burroughs Wellcome Scholar Award in Molecular Pathogenic Mycology, 1998-2005
Gyore, J., Parameswar, A.R., Hebbard, C., Oh, Y., Bi, E., Demchenko, A.V., Price, N.P., and Orlean, P. (2014) 2-Acylamido analogues of N-acetylglucosamine prime formation of chitin oligosaccharides by yeast chitin synthase 2. Journal of Biological Chemistry doi:10.1074/jbc.M114.550749
Zhang, Y., Askim, J.R., Zhong, W., Orlean, P., and Suslick, K.S. (2014) Identification of pathogenic fungi with an optoelectronic nose. Analyst, 2014 Feb 26. [Epub ahead of print]
Orlean, P. (2012) Architecture and Biosynthesis of the Yeast Cell Wall. In: YeastBook. Cell Signaling & Development (P. Pryciak and J. Thorner, Eds.) Genetics, 192: 775-818.
Oh, Y., Chang, K.-J., Orlean, P., Wloka, C., Deshaies, R., and Bi, E. (2012) Mitotic exit kinase Dbf2 directly phosphorylates chitin synthase Chs2 to regulate cytokinesis in budding yeast. Mol. Biol. Cell 23: 2445-2456.
Scarcelli, J.J., Colussi, P.A., Fabre, A.-L., Keller, M., Boles, E., Orlean, P., and Taron, C.H. (2012) Uptake of radiolabeled GlcNAc into Saccharomyces cerevisiae via native hexose transporters and its in vivo incorporation into GPI precursors in cells expressing heterologous GlcNAc kinase. FEMS Yeast Research 12: 305-316.
Orlean, P. and Menon, A.K. (2007) GPI anchoring of protein in yeast and mammalian cells or: how we learned to stop worrying and love glycophospholipids. Journal of Lipid Research 48: 993-1011.