1G8Y

CRYSTAL STRUCTURE OF THE HEXAMERIC REPLICATIVE HELICASE REPA OF PLASMID RSF1010

Summary for 1G8Y

• Entry DOI: 10.2210/pdb1g8y/pdb
• Descriptor: REGULATORY PROTEIN REPA (2 entities in total)
• Functional Keywords: p-loop, transcription
• Biological source: Escherichia coli
• Total number of polymer chains: 12
• Total formula weight: 359342.27

Authors

Niedenzu, T.,Roeleke, D.,Bains, G.,Scherzinger, E.,Saenger, W. (deposition date: 2000-11-21, release date: 2001-02-14, Last modification date: 2024-02-07)

Primary citation

Niedenzu, T.,Roleke, D.,Bains, G.,Scherzinger, E.,Saenger, W.
Crystal structure of the hexameric replicative helicase RepA of plasmid RSF1010.
J.Mol.Biol., 306:479-487, 2001

PubMed Abstract: Unwinding of double-stranded DNA into single-stranded intermediates required for various fundamental life processes is catalyzed by helicases, a family of mono-, di- or hexameric motor proteins fueled by nucleoside triphosphate hydrolysis. The three-dimensional crystal structure of the hexameric helicase RepA encoded by plasmid RSF1010 has been determined by X-ray diffraction at 2.4 A resolution. The hexamer shows an annular structure with 6-fold rotational symmetry and a approximately 17 A wide central hole, suggesting that single-stranded DNA may be threaded during unwinding. Homologs of all five conserved sequence motifs of the DnaB-like helicase family are found in RepA, and the topography of the monomer resembles RecA and the helicase domain of the bacteriophage T7 gp4 protein. In a modeled complex, ATP molecules are located at the subunit interfaces and clearly define adenine-binding and ATPase catalytic sites formed by amino acid residues located on adjacent monomers; most remarkable is the "arginine finger" Arg207 contributing to the active site in the adjacent monomer. This arrangement of active-site residues suggests cooperativity between monomers in ATP hydrolysis and helicase activity of RepA. The mechanism of DNA unwinding remains elusive, as RepA is 6-fold symmetric, contrasting the recently published asymmetric structure of the bacteriophage T7 gp4 helicase domain.

PubMed: 11178907
DOI: 10.1006/jmbi.2000.4398

Experimental method

X-RAY DIFFRACTION (2.4 Å)