1e0k
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GP4D HELICASE FROM PHAGE T7
OverviewOverview
We have determined the crystal structure of an active, hexameric fragment of the gene 4 helicase from bacteriophage T7. The structure reveals how subunit contacts stabilize the hexamer. Deviation from expected six-fold symmetry of the hexamer indicates that the structure is of an intermediate on the catalytic pathway. The structural consequences of the asymmetry suggest a "binding change" mechanism to explain how cooperative binding and hydrolysis of nucleotides are coupled to conformational changes in the ring that most likely accompany duplex unwinding. The structure of a complex with a nonhydrolyzable ATP analog provides additional evidence for this hypothesis, with only four of the six possible nucleotide binding sites being occupied in this conformation of the hexamer. This model suggests a mechanism for DNA translocation.
About this StructureAbout this Structure
1E0K is a Single protein structure of sequence from Bacteriophage t7. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of T7 gene 4 ring helicase indicates a mechanism for sequential hydrolysis of nucleotides., Singleton MR, Sawaya MR, Ellenberger T, Wigley DB, Cell. 2000 Jun 9;101(6):589-600. PMID:10892646
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