1g8y
From Proteopedia
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CRYSTAL STRUCTURE OF THE HEXAMERIC REPLICATIVE HELICASE REPA OF PLASMID RSF1010
Overview
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.
About this Structure
1G8Y is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Crystal structure of the hexameric replicative helicase RepA of plasmid RSF1010., Niedenzu T, Roleke D, Bains G, Scherzinger E, Saenger W, J Mol Biol. 2001 Feb 23;306(3):479-87. PMID:11178907
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