PMID:18000058

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Citation

Nakamura, A, Wada, C and Miki, K (2007) Structural basis for regulation of bifunctional roles in replication initiator protein. Proc. Natl. Acad. Sci. U.S.A. 104:18484-9

Abstract

DNA replication initiator protein RepE stringently regulates F plasmid replication by its two distinct molecular association states. A predominant dimer functions as an autogenous repressor, whereas monomers act as replication initiators, and the dimer requires actions of the DnaK molecular chaperone system for monomerization. The structure of the monomeric form is known, whereas the dimeric structure and structural details of the dimer-to-monomer conversion have been unclear. Here we present the crystal structure of the RepE dimer in complex with the repE operator DNA. The dimerization interface is mainly formed by intermolecular beta-sheets with several key interactions of charged residues. The conformations of the internal N- and C-terminal domains are conserved between the dimer and monomer, whereas the relative domain orientations are strikingly different, allowing for an efficient oligomeric transition of dual-functional RepE. This domain relocation accompanies secondary structural changes in the linker connecting the two domains, and the linker is included in plausible DnaK/DnaJ-binding regions. These findings suggest an activation mechanism for F plasmid replication by RepE monomerization, which is induced and mediated by the DnaK system.

Links

PubMed PMC2141803 Online version:10.1073/pnas.0705623104

Keywords

Amino Acid Sequence; Base Sequence; Crystallography, X-Ray; DNA Helicases/chemistry; DNA Helicases/genetics; DNA Helicases/metabolism; DNA-Binding Proteins/chemistry; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; Dimerization; Models, Molecular; Molecular Chaperones/chemistry; Molecular Chaperones/metabolism; Molecular Sequence Data; Protein Binding; Protein Structure, Quaternary; Protein Structure, Tertiary; Sequence Alignment; Sequence Homology, Amino Acid; Structural Homology, Protein; Trans-Activators/chemistry; Trans-Activators/genetics; Trans-Activators/metabolism

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