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A Single subunit directs the assembly of the escherichia coli DNA sliding clamp loader

Journal Article


Abstract


  • Multi-protein clamp loader complexes are required to load sliding clamps onto DNA. In Escherichia coli the clamp loader contains three DnaX (tau/gamma) proteins, delta, and delta', which together form an asymmetric pentameric ring that also interacts with psi chi. Here we used mass spectrometry to examine the assembly and dynamics of the clamp loader complex. We find that gamma exists exclusively as a stable homotetramer, while tau is in a monomer-dimer-trimer-tetramer equilibrium. delta' plays a direct role in the assembly as tau/gamma oligomer breaker, thereby facilitating incorporation of lower oligomers. With delta', both delta and psi chi stabilize the trimeric form of DnaX, thus completing the assembly. When tau and gamma are present simultaneously, mimicking the situation in vivo, subunit exchange between tau and gamma tetramers occurs rapidly to form heterocomplexes but is retarded when delta delta' is present. The implications for intracellular assembly of the DNA polymerase III holoenzyme are discussed.

Authors


  •   Park, Ah-Young (external author)
  •   Jergic, Slobodan
  •   Politis, Argyris (external author)
  •   Ruotolo, Brandon T. (external author)
  •   Hirshberg, Daniel (external author)
  •   Jessop, Linda (external author)
  •   Beck, Jennifer L.
  •   Barsky, Daniel (external author)
  •   O'Donnell, M A (external author)
  •   Dixon, Nicholas E.
  •   Robinson, Carol V. (external author)

Publication Date


  • 2010

Citation


  • Park, A. Young., Jergic, S., Politis, A., Ruotolo, B. T., Hirshberg, D., Jessop, L. L., Beck, J. L., Barsky, D., O'Donnell, M., Dixon, N. E. & Robinson, C. V. (2010). A Single subunit directs the assembly of the escherichia coli DNA sliding clamp loader. Structure, 18 (3), 285-292.

Scopus Eid


  • 2-s2.0-77649103357

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5052

Number Of Pages


  • 7

Start Page


  • 285

End Page


  • 292

Volume


  • 18

Issue


  • 3

Abstract


  • Multi-protein clamp loader complexes are required to load sliding clamps onto DNA. In Escherichia coli the clamp loader contains three DnaX (tau/gamma) proteins, delta, and delta', which together form an asymmetric pentameric ring that also interacts with psi chi. Here we used mass spectrometry to examine the assembly and dynamics of the clamp loader complex. We find that gamma exists exclusively as a stable homotetramer, while tau is in a monomer-dimer-trimer-tetramer equilibrium. delta' plays a direct role in the assembly as tau/gamma oligomer breaker, thereby facilitating incorporation of lower oligomers. With delta', both delta and psi chi stabilize the trimeric form of DnaX, thus completing the assembly. When tau and gamma are present simultaneously, mimicking the situation in vivo, subunit exchange between tau and gamma tetramers occurs rapidly to form heterocomplexes but is retarded when delta delta' is present. The implications for intracellular assembly of the DNA polymerase III holoenzyme are discussed.

Authors


  •   Park, Ah-Young (external author)
  •   Jergic, Slobodan
  •   Politis, Argyris (external author)
  •   Ruotolo, Brandon T. (external author)
  •   Hirshberg, Daniel (external author)
  •   Jessop, Linda (external author)
  •   Beck, Jennifer L.
  •   Barsky, Daniel (external author)
  •   O'Donnell, M A (external author)
  •   Dixon, Nicholas E.
  •   Robinson, Carol V. (external author)

Publication Date


  • 2010

Citation


  • Park, A. Young., Jergic, S., Politis, A., Ruotolo, B. T., Hirshberg, D., Jessop, L. L., Beck, J. L., Barsky, D., O'Donnell, M., Dixon, N. E. & Robinson, C. V. (2010). A Single subunit directs the assembly of the escherichia coli DNA sliding clamp loader. Structure, 18 (3), 285-292.

Scopus Eid


  • 2-s2.0-77649103357

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5052

Number Of Pages


  • 7

Start Page


  • 285

End Page


  • 292

Volume


  • 18

Issue


  • 3