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Simultaneous single-molecule measurements of phage T7 replisome composition and function reveal the mechanism of polymerase exchange

Journal Article


Abstract


  • A complete understanding of the molecular mechanisms underlying the functioning of large, multiprotein complexes requires experimental tools capable of simultaneously visualizing molecular architecture and enzymatic activity in real time. We developed a novel single-molecule assay that combines the flow-stretching of individual DNA molecules to measure the activity of the DNA-replication machinery with the visualization of fluorescently labeled DNA polymerases at the replication fork. By correlating polymerase stoichiometry with DNA synthesis of T7 bacteriophage replisomes, we are able to quantitatively describe the mechanism of polymerase exchange. We find that even at relatively modest polymerase concentration (∼2 nM), soluble polymerases are recruited to an actively synthesizing replisome, dramatically increasing local polymerase concentration. These excess polymerases remain passively associated with the replisome through electrostatic interactions with the T7 helicase for ∼50 s until a stochastic and transient dissociation of the synthesizing polymerase from the primer-template allows for a polymerase exchange event to occur.

Authors


  •   Loparo, Joseph J. (external author)
  •   Kulczyk, Arkadiusz W. (external author)
  •   Richardson, Charles C. (external author)
  •   van Oijen, Antoine M.

Publication Date


  • 2011

Citation


  • Loparo, J. J., Kulczyk, A. W., Richardson, C. C. & van Oijen, A. M. (2011). Simultaneous single-molecule measurements of phage T7 replisome composition and function reveal the mechanism of polymerase exchange. Proceedings of the National Academy of Sciences of USA, 108 (9), 3584-3589.

Scopus Eid


  • 2-s2.0-79952746781

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/2177

Has Global Citation Frequency


Number Of Pages


  • 5

Start Page


  • 3584

End Page


  • 3589

Volume


  • 108

Issue


  • 9

Place Of Publication


  • United States

Abstract


  • A complete understanding of the molecular mechanisms underlying the functioning of large, multiprotein complexes requires experimental tools capable of simultaneously visualizing molecular architecture and enzymatic activity in real time. We developed a novel single-molecule assay that combines the flow-stretching of individual DNA molecules to measure the activity of the DNA-replication machinery with the visualization of fluorescently labeled DNA polymerases at the replication fork. By correlating polymerase stoichiometry with DNA synthesis of T7 bacteriophage replisomes, we are able to quantitatively describe the mechanism of polymerase exchange. We find that even at relatively modest polymerase concentration (∼2 nM), soluble polymerases are recruited to an actively synthesizing replisome, dramatically increasing local polymerase concentration. These excess polymerases remain passively associated with the replisome through electrostatic interactions with the T7 helicase for ∼50 s until a stochastic and transient dissociation of the synthesizing polymerase from the primer-template allows for a polymerase exchange event to occur.

Authors


  •   Loparo, Joseph J. (external author)
  •   Kulczyk, Arkadiusz W. (external author)
  •   Richardson, Charles C. (external author)
  •   van Oijen, Antoine M.

Publication Date


  • 2011

Citation


  • Loparo, J. J., Kulczyk, A. W., Richardson, C. C. & van Oijen, A. M. (2011). Simultaneous single-molecule measurements of phage T7 replisome composition and function reveal the mechanism of polymerase exchange. Proceedings of the National Academy of Sciences of USA, 108 (9), 3584-3589.

Scopus Eid


  • 2-s2.0-79952746781

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/2177

Has Global Citation Frequency


Number Of Pages


  • 5

Start Page


  • 3584

End Page


  • 3589

Volume


  • 108

Issue


  • 9

Place Of Publication


  • United States