+Search query
-Structure paper
Title | Loading a ring: structure of the Bacillus subtilis DnaB protein, a co-loader of the replicative helicase. |
---|---|
Journal, issue, pages | J Mol Biol, Vol. 367, Issue 3, Page 764-769, Year 2007 |
Publish date | Mar 30, 2007 |
![]() | Rafael Núñez-Ramírez / Marion Velten / Germán Rivas / Patrice Polard / José María Carazo / Luis Enrique Donate / ![]() |
PubMed Abstract | Loading of the ring-shaped replicative helicase is a critical step in the initiation of DNA replication. Bacillus subtilis has adopted a two-protein strategy to load its hexameric replicative ...Loading of the ring-shaped replicative helicase is a critical step in the initiation of DNA replication. Bacillus subtilis has adopted a two-protein strategy to load its hexameric replicative helicase: DnaB and DnaI interact with the helicase and mediate its delivery onto DNA. We present here the 3D electron microscopy structure of the DnaB protein, along with a detailed analysis of both its oligomeric state and its domain organization. DnaB is organized as an asymmetric tetramer that is comprised of two stacked components, one arranged as a closed collar and the other as an open sigma shape. Intriguingly, the 3D map of DnaB exhibits an overall architecture similar to the structure of the Escherichia coli gamma-complex, the loader of the ring-shaped processivity factor. We propose a model whereby each DnaB monomer participates in both stacked components of the tetramer and displays a different overall shape. This asymmetric quaternary organization could be a general feature of ring loaders. |
![]() | ![]() ![]() |
Methods | EM (single particle) |
Resolution | 24.0 Å |
Structure data | ![]() EMDB-1225: |
Source |
|