1T3W: Crystal Structure Of The E.coli Dnag C-terminal Domain (residues 434 To 581)

During bacterial DNA replication, the DnaG primase interacts with the hexameric DnaB helicase to synthesize RNA primers for extension by DNA polymerase. In Escherichia coli, this occurs by transient interaction of primase with the helicase. Here we demonstrate directly by surface plasmon resonance that the C-terminal domain of primase is responsible for interaction with DnaB6. Determination of the 2.8-angstroms crystal structure of the C-terminal domain of primase revealed an asymmetric dimer. The monomers have an N-terminal helix bundle similar to the N-terminal domain of DnaB, followed by a long helix that connects to a C-terminal helix hairpin. The connecting helix is interrupted differently in the two monomers. Solution studies using NMR showed that an equilibrium exists between a monomeric species with an intact, extended but naked, connecting helix and a dimer in which this helix is interrupted in the same way as in one of the crystal conformers. The other conformer is not significantly populated in solution, and its presence in the crystal is due largely to crystal packing forces. It is proposed that the connecting helix contributes necessary structural flexibility in the primase-helicase complex at replication forks.
PDB ID: 1T3WDownload
MMDB ID: 29906
PDB Deposition Date: 2004/4/28
Updated in MMDB: 2004/12
Experimental Method:
x-ray diffraction
Resolution: 2.8  Å
Source Organism:
Similar Structures:
Biological Unit for 1T3W: monomeric; determined by author
Molecular Components in 1T3W
Label Count Molecule
Protein (1 molecule)
DNA Primase(Gene symbol: dnaG)
Molecule annotation
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Citing MMDB