The C-terminal domain of DNA gyrase A adopts a DNA-bending beta-pinwheel fold.
DNA gyrase is unique among enzymes for its ability to actively introduce negative supercoils into DNA. This function is mediated in part by the C-terminal domain of its A subunit (GyrA CTD). Here, we report the crystal structure of this approximately 35-kDa domain determined to 1.75-A resolution. The GyrA CTD unexpectedly adopts an unusual fold, which we term a beta-pinwheel, that is globally reminiscent of a beta-propeller but is built of blades with a previously unobserved topology. A large, conserved basic patch on the outer edge of this domain suggests a likely site for binding and bending DNA; fluorescence resonance energy transfer-based assays show that the GyrA CTD is capable of bending DNA by > or =180 degrees over a 40-bp region. Surprisingly, we find that the CTD of the topoisomerase IV A subunit, which shares limited sequence homology with the GyrA CTD, also bends DNA. Together, these data provide a physical explanation for the ability of DNA gyrase to constrain a positive superhelical DNA wrap, and also suggest that the particular substrate preferences of topoisomerase IV might be dictated in part by the function of this domain.
Corbett
Kevin D
KD
Department of Molecular and Cellular Biology, 237 Hildebrand Hall 3206, University of California, Berkeley, CA 94720-3206, USA.
Shultzaberger
Ryan K
RK
Berger
James M
JM
D001483:Base Sequence; D027081:DNA Gyrase / Q000737:chemistry*; D017931:DNA Primers; D004269:DNA, Bacterial / Q000737:chemistry*; D004926:Escherichia coli / Q000201:enzymology; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D055672:Static Electricity
D017931:DNA Primers; D004269:DNA, Bacterial; D027081:DNA Gyrase