Sandbox20: Difference between revisions

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It is known with some certainty that the RTP dimer adopts an asymmetric arrangement upon binding of the TerB site. In the [[2efw| C110S mutant]] complexed with the native TerB sequence, the two subunits interact differently with the DNA bases to produce wing-up and wing-down conformations. These can be distinguished by the angle the a2 helix makes with the a3 helix indicated in this <scene name='Sandbox20/2efw/14'>model</scene>. It is likely that asymmetry is also introduced when the RTP dimer binds to the TerA site, but the crystal structure of this complex has not been solved.
It is known with some certainty that the RTP dimer adopts an asymmetric arrangement upon binding of the TerB site. In the [[2efw| C110S mutant]] complexed with the native TerB sequence, the two subunits interact differently with the DNA bases to produce wing-up and wing-down conformations. These can be distinguished by the angle the a2 helix makes with the a3 helix indicated in this <scene name='Sandbox20/2efw/14'>model</scene>. It is likely that asymmetry is also introduced when the RTP dimer binds to the TerA site, but the crystal structure of this complex has not been solved.


Although the TerA site inherently has a lower binding affinity for RTP, as evident from the larger dissociation constant associated with the RTP-TerA complex, positive cooperativity from the binding of RTP to TerB facilitates the binding of RTP to TerA. It is proposed that RTP bends the DNA at the TerB site in a manner that favours RTP binding at TerA. The RTP dimer at TerB may also present a surface for stabilising interactions with the dimer at TerA. This is believed to happen through the b1 loop and b3 strand (need to standardise the names)
The dissociation constant of the RTP-TerA complex is greater than that of RTP-TerB, indicating an inherently a lower binding affinity. However, following the binding of RTP to TerA, a positive cooperative effect facilitates the binding of RTP to TerA (Reference!). It has been proposed that RTP bends the DNA at the TerB site in a manner that favours RTP binding at TerA. The RTP dimer at TerB may also present a surface for stabilising interactions with the dimer at TerA through its β1 loop and β3 strand.


=== Replication Termination Activity===
=== Replication Termination Activity===