Structural Basis for Replication Origin Unwinding by An Initiator-Primase of Plasmid ColE2-P9: Duplex DNA Unwinding by A Single Protein [Protein Structure and Folding]

December 23rd, 2014 by Itou, H., Yagura, M., Shirakihara, Y., Itoh, T.

Duplex DNA is generally unwound by protein oligomers prior to replication. The Rep protein of plasmid ColE2-P9 (34 kDa) is an essential initiator for plasmid DNA replication. This protein binds the replication origin (Ori) in a sequence specific manner as a monomer and unwinds DNA. Here we present the crystal structure of the DNA-binding domain of Rep (E2Rep-DBD) in complex with Ori DNA. The structure unveils the basis for Ori specific recognition by the E2Rep-DBD and also reveals that it unwinds DNA by the concerted actions of its three contiguous structural modules. The structure also shows that the functionally unknown PriCT domain, which forms a compact module, plays a central role in DNA unwinding. The conservation of the PriCT domain in the C-termini of some archaeo-eukaryotic primases, indicates that it likely plays a similar role in these proteins. Thus, this is the first report providing the structural basis for the functional importance of the conserved PriCT domain and also reveals a novel mechanism for DNA unwinding by a single protein.
  • Posted in Journal of Biological Chemistry, Publications
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