2pjr
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(New page: 200px<br /><applet load="2pjr" size="450" color="white" frame="true" align="right" spinBox="true" caption="2pjr, resolution 2.9Å" /> '''HELICASE PRODUCT COMP...)
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Revision as of 11:26, 21 November 2007
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HELICASE PRODUCT COMPLEX
Overview
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 Structure
2PJR is a Protein complex structure of sequences from Geobacillus stearothermophilus with SO4 as ligand. Full crystallographic information is available from OCA.
Reference
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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