The DNA polymerase III holoenzyme of E. coli is a prototypical replicative complex, exhibiting properties in common with other cellular replicases, including a high rate of processive elongation and the ability to interact with other proteins at the replication fork, establishing the communication channels necessary to coordinate the events required for efficient chromosomal replication. A key component of all cellular replicases is a multisubunit assembly of homologous proteins that require ATP to assemble a """"""""sliding clamp processivity factor"""""""" onto primer termini. In E. coli, this function is served by the DnaX complex, DnaX3deltadelta'/khi/psi. The dna X gene of E. coli encodes two distinct products: i, the full-length translation product and gamma, a shorter protein that arises by translational frameshifting. During the next grant period, we will study i) the assembly pathway of DNA polymerase III holoenzyme, with emphasis on the role of Pol III in steering the assembly pathway to permit a unique arrangement of DnaX subunits, ii) determine the changes in macromolecular interactions that occur during loading of the beta2 sliding clamp onto primed DNA by the DnaX complex 'clamp loader,' iii) determine the mechanism of ATPgammaS-assisted initiation complex formation that proceeds without nucleotide hydrolysis and iv) study the chaperone-like properties of DnaX in initiation complex formation.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
7R01GM035695-20
Application #
7275651
Study Section
Special Emphasis Panel (ZRG1-MGA (01))
Program Officer
Dearolf, Charles R
Project Start
1985-12-01
Project End
2009-02-28
Budget Start
2006-09-01
Budget End
2007-02-28
Support Year
20
Fiscal Year
2006
Total Cost
$74,500
Indirect Cost
Name
University of Colorado at Boulder
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
007431505
City
Boulder
State
CO
Country
United States
Zip Code
80309
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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