Sandbox20: Difference between revisions
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The asymmetry of the dimer is shown by the names 'wing up' and 'wing down'. It is measured by the angle between the a2 and a3 heices, as shown <scene name='Sandbox20/2efw/14'>by clicking here</scene>. | The asymmetry of the dimer is shown by the names 'wing up' and 'wing down'. It is measured by the angle between the a2 and a3 heices, as shown <scene name='Sandbox20/2efw/14'>by clicking here</scene>. | ||
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=== Replication Termination Activity=== | === Replication Termination Activity=== | ||
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[[Image:Tus 1 labelled helices.jpg | thumb | upright=1.6| left| Secondary structures of the Tus protein.]] | [[Image:Tus 1 labelled helices.jpg | thumb | upright=1.6| left| Secondary structures of the Tus protein.]] | ||
The structure of the Tus protein was determined in complex with TerA by Kamada et al., and shown to be a previously undescribed backbone conformation (<scene name='Sandbox20/Tus/2'>original image</scene>.). It is divided into two domains (amino and carboxy), in which α-helical regions of each are spanned by a central β-sandwich which contacts 13 bp of DNA duplex (#Indicate domains). Three helices within the amino domain (αI αII, αIII) form an antiparallel bundle aligned parallel to the DNA (#Helix bundle). Another two helices (αIV, αV) clamp the DNA phosphate backbone at the non-permissive end, and forms the cytosine-specific pocket containing the crucial residues for anti-helicase activity (#Phosphate clamp). The main DNA-binding domain however is the exposed side of the double β sheet layer which provides several base-specific interactions. This lies within the major groove and causes a conformational change in the DNA involving a deepening of the major groove, and an expansion of the minor one (#Sheet position). | The structure of the Tus protein was determined in complex with TerA by Kamada et al., and shown to be a previously undescribed backbone conformation (<scene name='Sandbox20/Tus/2'>original image</scene>.). It is divided into two domains (amino and carboxy), in which α-helical regions of each are spanned by a central β-sandwich which contacts 13 bp of DNA duplex (#Indicate domains). [[Image:RTP Dimerisation.jpg | thumb | upright=1.6| right| Interactions between a4 helices facilitates dimerisation of RTP on the Ter DNA site.]] Three helices within the amino domain (αI αII, αIII) form an antiparallel bundle aligned parallel to the DNA (#Helix bundle). Another two helices (αIV, αV) clamp the DNA phosphate backbone at the non-permissive end, and forms the cytosine-specific pocket containing the crucial residues for anti-helicase activity (#Phosphate clamp). The main DNA-binding domain however is the exposed side of the double β sheet layer which provides several base-specific interactions. This lies within the major groove and causes a conformational change in the DNA involving a deepening of the major groove, and an expansion of the minor one (#Sheet position). | ||
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===DNA Binding=== | ===DNA Binding=== | ||