The DNA polymerase Ill holoenzyme is the replicative complex of E. coli, responsible for the synthesis of the majority of the chromosome. The holoenzyme contains at least 10 different subunits, most present in two or more copies, forming a complex of approximately 800,000 daltons. This replicative complex exhibits many properties that distinguish it from simpler polymerases. These properties include a high rate of elongation, the ability to form an ATP-dependent highly processive clamp on the DNA template, and the ability to function as an asymmetric dimer with distinguishable leading and lagging strand polymerases. Our knowledge of the function of this enzyme surpasses our knowledge of its structure. We need to know the subunit arrangements of this enzyme and its points of contact with the template-primer so that more sophisticated testable hypotheses can be formulated regarding the function of the individual components. We intend to take a tripartite approach to establishing the structure of the DNA polymerase III holoenzyme at the level of subunit arrangement. The points of subunit-template and subunit-primer contact will be identified by a photo-affinity labeling approach. We will make a series of'template-primers each containing a photo-affinity label attached to a unique nucleotide. Identification of which subunits cross-link to each template-primer will identify a contact and will provide orientation points upon which we can build up a holoenzyme structure. (ii) We will identify subunit contacts by chemical cross-linking. This will permit us to assemble a group of testable structures for holoenzyme. (iii) Fluorescence energy transfer will be used to determine distances between the template-primer, active sites and individual subunits. This will provide checks of the results obtained by the techniques described above and will provide information about the spatial relationship of subunits not obtained by other methods. We also intend to address structural issues regarding the asymmetric dimer hypothesis for the DNA polymerase III holoenzyme.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM035695-06A1
Application #
3288748
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1985-12-01
Project End
1995-06-30
Budget Start
1991-07-01
Budget End
1992-06-30
Support Year
6
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Colorado Denver
Department
Type
Schools of Medicine
DUNS #
065391526
City
Aurora
State
CO
Country
United States
Zip Code
80045
Downey, Christopher D; McHenry, Charles S (2010) Chaperoning of a replicative polymerase onto a newly assembled DNA-bound sliding clamp by the clamp loader. Mol Cell 37:481-91
Yuan, Quan; McHenry, Charles S (2009) Strand displacement by DNA polymerase III occurs through a tau-psi-chi link to single-stranded DNA-binding protein coating the lagging strand template. J Biol Chem 284:31672-9
Jarvis, Thale C; Beaudry, Amber A; Bullard, James M et al. (2005) Discovery and characterization of the cryptic psi subunit of the pseudomonad DNA replicase. J Biol Chem 280:40465-73
Bullard, James M; Pritchard, Arthur E; Song, Min-Sun et al. (2002) A three-domain structure for the delta subunit of the DNA polymerase III holoenzyme delta domain III binds delta' and assembles into the DnaX complex. J Biol Chem 277:13246-56
Glover, B P; McHenry, C S (2001) The DNA polymerase III holoenzyme: an asymmetric dimeric replicative complex with leading and lagging strand polymerases. Cell 105:925-34
Song, M S; Pham, P T; Olson, M et al. (2001) The delta and delta ' subunits of the DNA polymerase III holoenzyme are essential for initiation complex formation and processive elongation. J Biol Chem 276:35165-75
Song, M S; McHenry, C S (2001) Carboxyl-terminal domain III of the delta' subunit of DNA polymerase III holoenzyme binds DnaX and supports cooperative DnaX complex assembly. J Biol Chem 276:48709-15
Glover, B P; Pritchard, A E; McHenry, C S (2001) tau binds and organizes Escherichia coli replication proteins through distinct domains: domain III, shared by gamma and tau, oligomerizes DnaX. J Biol Chem 276:35842-6
Song, M S; Dallmann, H G; McHenry, C S (2001) Carboxyl-terminal domain III of the delta' subunit of the DNA polymerase III holoenzyme binds delta. J Biol Chem 276:40668-79
Gao, D; McHenry, C S (2001) Tau binds and organizes Escherichia coli replication proteins through distinct domains. Domain III, shared by gamma and tau, binds delta delta ' and chi psi. J Biol Chem 276:4447-53

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