3pjr
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HELICASE SUBSTRATE COMPLEX
OverviewOverview
We have determined two different structures of PcrA DNA helicase complexed with the same single strand tailed DNA duplex, providing snapshots of different steps on the catalytic pathway. One of the structures is of a complex with a nonhydrolyzable analog of ATP and is thus a "substrate" complex. The other structure contains a bound sulphate ion that sits in a position equivalent to that occupied by the phosphate ion produced after ATP hydrolysis, thereby mimicking a "product" complex. In both complexes, the protein is monomeric. Large and distinct conformational changes occur on binding DNA and the nucleotide cofactor. Taken together, these structures provide evidence against an "active rolling" model for helicase action but are instead consistent with an "inchworm" mechanism.
About this StructureAbout this Structure
3PJR is a Single protein structure of sequence from Geobacillus stearothermophilus with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of complexes of PcrA DNA helicase with a DNA substrate indicate an inchworm mechanism., Velankar SS, Soultanas P, Dillingham MS, Subramanya HS, Wigley DB, Cell. 1999 Apr 2;97(1):75-84. PMID:10199404
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