SUNY at Albany
June 19-23, 2001
The Polymerases of Replication and Transcription
We have determined the crystal structures of several polynucleotide polymerase involved both in DNA replication and in DNA-dependent RNA transcription. We have now established the structures of the phage RB69 DNA polymerase, a member of the eukaryotic pol family of replicating polymerases, as the apo enzyme, the complex with primer-template DNA bound at the editing active site and the ternary complex with primer-template DNA and deoxynucleoside triphosphate bound at the polymerase active site. Not only does the fingers domain rotate by 60o upon formation of the ternary complex, analogous to the conformational changes observed in other DNA polymerases, but the orientation of the duplex product differs by 40o between the polymerizing and editing complexes necessitating the flexible attachment of the sliding clamp to the polymerase. We have also established the structure of a catalytically active fragment of a DNA polymerase that is homologous to E. coli dinB polymerase, a polymerase capable of lesion bypass synthesis. This structure suggests explanations for the different functional properties observed for this family of DNA polymerase.
The crystal structures of T7 RNA polymerase complexed with (1) a transcription inhibitor, T7 lysozyme, (2) an open promoter DNA and (3) a transcribing promoter including 3 nucleotides that transcribed RNA and deoxynucleoside triphosphate have been determined. These structures explain many of the known functional differences between DNA and RNA polymerases.
T.A. Steitz (1,2,3), M.C. Franklin (1), B.L. Zhou (1), J. Pata (1), Y. Shamoo (1), J. Wang (1), G.M.T. Cheetham (1) and D. Jeruzalmi (1).
Department of Molecular Biophysics and Biochemistry (1), Yale University, Department of Chemistry (2), Yale University and the Howard Hughes Medical Institute (3),