Poster abstracts

Poster number 11 submitted by Bryon Mahler

Solution Structure of Deoxynucleotide N-glycosidase Rcl

Bryon Mahler (Department of Biochemistry, The Ohio State University), Kiran Doddapaneni (Department of Biochemistry, The Ohio State University), Ryan Pavlovicz (College of Pharmacy, The Ohio State University), Chenglong Li (College of Pharmacy, The Ohio State University), Zhengrong Wu (Department of Biochemistry, The Ohio State University)

Abstract:
RCL (deoxynucleoside 5’-monophosphate N-glycosidase), one of the most responsive targets to c-Myc, can aid in independent cell growth and tumor formation. Significant up-regulation of RCL has been noticed in selective cancers such as breast cancer, prostate cancer, lymphoma and glioblastoma. Overexpression of this protein is in correlation with increased intracellular nucleotide pool in tumor, and therefore it may represent a family of non-canonical nucleotide salvage enzymes. Unlike its closest relative, nucleoside 2-deoxyribosyltransferases, RCL preferentially hydrolyzes the glycosidic bond in deoxypurine nucleotides in a non-reversible reaction. The enzymatic products, purine nucleobase and deoxyribose-5-phosphate, have direct roles in tumor neoplastic growth and angiogenesis, respectively. Therefore RCL could be a prime therapeutic cancer target.
The solution structure of RCL has been determined by multidimensional triple resonance NMR spectroscopy utilizing both backbone dihedral angle and distance restraints supplemented with residual dipolar couplings. RCL is a symmetric dimer with each monomer comprising a five-stranded b-sheet sandwiched between five a-helixes, three of which form the dimer interface allowing two monomers pack side-by-side. Residues around the putative substrate binding site show significant conformational variation, with one of the conformer closely resembling the inhibitor, GMP, bound state. Upon GMP binding, all conformation converge to a single form, suggesting that protein dynamics is important for the enzymatic function of apo-RCL. Compared to the structures of the deoxyribosyltransferases, significant differences are observed in the substrate binding pocket and the C-terminal tail. Serving as a novel N-glycosidase, RCL structure may provide invaluable insight into the mechanism of such enzyme, and allow structural based rational drug design.

References:
1. Ghiorghi, YK., Zeller, KI., Dang, CV and Kaminski, PA. (2007) JBC 282:8150-8156
2. Shin, S., Bosc, D., Ingle, J., Spelsberg, T., and Janknecht, R. (2008) J Cell Biochem 105:866-874
3. Armstrong, S., Cook, W., Short, S., and Ealick, S. (1996) Structure 4:97-107

Keywords: Solution structure, NMR, Drug Target