1e0k: Difference between revisions

[[Image:1e0k.jpg|left|200px]]<br /><applet load="1e0k" size="350" color="white" frame="true" align="right" spinBox="true"  

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.

1E0K is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacteriophage_t7 Bacteriophage t7]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1E0K OCA].  

[[Category: Sawaya, M R.]]

[[Category: Singleton, M R.]]

[[Category: Wigley, D B.]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:22:30 2008''