Millie M. Georgiadis, Ph.D.

Associate Professor Biological Chemistry and Crystallography B.S., Indiana University 1984 Ph.D., University of California, Los Angeles 1990   Phone: (317) 278-8486 Email: mgeorgia@iupui.edu

Research in my laboratory is directed toward understanding the role of protein-nucleic acid interactions in such fundamental biological processes as replication, nuclear export, and regulation of gene expression. Our approach is to integrate X-ray crystallographic studies with complementary biochemical studies. Current research efforts are focused on understanding in atomic detail two critical steps in the retroviral life cycle: (1) replication of the retroviral genome by reverse transcriptase and (2) nuclear export of unspliced retroviral transcripts including the constitutive transport element (CTE). These studies are related more generally to (1) the understanding of nucleic acid interactions that are important during replication through comparative analysis with related polymerases and (2) nuclear export of mRNA, which is mediated by the same host factor, Tap.

Reverse transcriptase (RT) is a relatively simple replicative polymerase by comparison with its mammalian counterparts and is therefore an ideal enzyme for studying the complicated process of polymerization. The epidemic outbreak of AIDS caused by human immunodeficiency virus (HIV) has focused a great deal of research efforts on HIV-1 RT. Drugs that are presently being used to treat AIDS patients include several inhibitors of HIV-1 RT, which continues to be a target for development of new inhibitors. We have focused our efforts on the Moloney murine leukemia virus (MMLV) RT, a related retroviral RT, with the goal of understanding the mechanism of the processive DNA synthesis and interactions with nucleic acid. Basic and detailed knowledge of catalysis and substrate interactions in RT will further efforts in the development of effective inhibitors.

We have determined X-ray crystallographic structures of several novel DNA complexes with the N-terminal fragment of MMLV RT. Our structural analysis and subsequent biochemical and retroviral work has led to the discovery of a novel binding site for nucleic acid and proposed mechanism for processive DNA synthesis. In addition, we have determined the crystal structure of the RNA-binding domain of human protein, Tap, which mediates nuclear export of mRNA. Through structure-based mutational analysis of this domain of Tap, we have proposed a novel RNA-interacting surface. Future structural work will focus on biologically relevant nucleic acid complexes of the full-length MMLV RT and human Tap protein.

A second area of interest is in understanding the role of nucleic acid interactions that regulate temporal gene expression during meiosis in yeast. This system serves as a model system for understanding mechanisms that control development in higher eukaryotes. We have recently determined the crystal structure of a novel DNA-binding domain from Ndt80, a transcriptional activator required for meiosis in yeast. Our structural studies revealed that Ndt80 has a novel structure as well as a novel DNA-binding motif and is the founding member of a new family of transcription factors including a human protein that has been reported to be highly expressed in invasive tumor cells. Future work on this project includes structural studies of relevant nucleic acid complexes with Ndt80 and other factors involved in the regulation of meiosis. We are also interested in characterizing additional members of this new family of transcription factors.

Recent Publications

K. D. Goodwin, M. A. Lewis, E. C. Long, and M. M. Georgiadis "The crystal structure of DNA-bound Co(III)•bleomycin B2: Insights on intercalation and minor groove binding" Proc. Natl. Acad. Sci., U.S.A. 2008, 105, in press.

Y. Roman, M. Oshige, Y. J. Lee, K. D. Goodwin, M. M. Georgiadis, R. A. Hromas, and S. H. Lee "Biochemical Characterization of a SET and Transposase Fusion Protein, Metnase: Its DNA Binding and DNA Cleavage Activity" Biochemistry 2007, 46, 11369-11376.

F. Tanious, W. Laine, P. Peixoto, C. Bailly, K. D. Goodwin, M. A. Lewis, E. C. Long, M. M. Georgiadis, R. Tidwell, and W. D. Wilson "Unusually strong binding to the DNA minor groove by a highly twisted benzimidazole-diphenylether: Induced fit and bound water" Biochemistry 2007, 46, 6944-6956.

Y. Luo, H. J. Kwon, S. Montano, M. M. Georgiadis, M. G. Goebl, and M. A. Harrington "Phosphorylation of SIMPL modulates RelA-associated NF- kappaB-dependent transcription" Am. J. Physiol. Cell Physiol. 2007, 292, C1013-1023.

S. P. Montano, M. L. Cote, M. J. Roth, and M. M. Georgiadis "Crystal structures of oligonucleotides including the integrase processing site of the Moloney murine leukemia virus" Nucleic Acids Res. 2006, 34, 5353-5360.

K. D. Goodwin, M. A. Lewis, F. A. Tanious, R. R. Tidwell, W. D. Wilson, M. M. Georgiadis, and E. C. Long "A high-throughput, high-resolution strategy for the study of site selective DNA binding agents: Analysis of a "highly-twisted" benzamidazole diamidine" J. Am. Chem. Soc. 2006, 128, 7846-7854.

E. Haag-Breese, V. N. Uversky, M. M. Georgiadis and M. A. Harrington "The disordered amino-terminus of SIMPL interacts with members of the 70-kDa heat-shock protein family" DNA Cell Biol. 2006, 25, 704-714.

R. L. Crowther and M. M. Georgiadis, M. M. "The crystal structure of 5-keto-4-deoxyuronate isomerase from Eschericia coli." Proteins 2005, 61, 680-684.

K. D. Goodwin, E. C. Long, and M. M. Georgiadis "A host-guest approach for determining DNA-drug interactions: An example using netropsin" Nucl. Acids Res. 2005, 33, 4106-4116.

R. L. Crowther, D. P. Remeta, C. Minetti, D. Das, S. P. Montano and M. M. Georgiadis "Structural and energetic characterization of nucleic acid binding to the fingers domain of Moloney murine leukemia virus reverse transcriptase" Proteins 2004, 57,15-26.

I. Fingerman, K. Sutphen, S. P. Montano, M. M. Georgiadis and A. K. Vershon "Characterization of critical interactions between Ndt80 and MSE-DNA defining a novel family of Ig-fold transcription factors" Nucl. Acids. Res. 2004, 25, 2947-2956.

D. Das and M. M. Georgiadis "The crystal structure of the monomeric reverse transcriptase from Moloney murine leukemia virus" Structure 2004, 12, 819-829.

M. Pierce, K. R. Benjamin, S. P. Montano, M.M. Georgiadis, E. Winter and A. K. Vershon "Sum1 and Ndt80 proteins compete for binding to MSE sequences that control meiotic gene expression" Mol. Cell Biol. 2003, 23, 4814-4825.

R. A. Villanueva, C. Rivera, C. B. Jonsson, M. M. Georgiadis and M. J. Roth "Differential multimerization of Moloney murine leukemia virus integrase purified under non-denaturing conditions" Virology 2003, 316,146-160.

M. L. Cote, M. Plomm, and M. M. Georgiadis "Staying straight with A-tracts: A DNA analogue of the HIV-1 polypurine tract" J. Mol. Biol. 2003, 330, 57-74.

D. N. Ho, G. A. Coburn, Y. Kang, B. R. Cullen and M. M. Georgiadis "The crystal structure and mutational anlaysis of a novel RNA-binding domain found in the human Tap nuclear mRNA export factor" Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 1888-1893.

S. P. Montano, M. L. Cote, I. Fingerman, M. Pierce, A. K. Vershon and M. M. Georgiadis "The crystal structure of a novel DNA-binding domain from Ndt80, a transcriptional activator required for meiosis in yeast" Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 14041-14046.