User:David Jung/BCHM3981 RTP Tus
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RTP Tus test
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Differential binding affinity model
For each terminator site (Ter site), two dimers of RTP bind. Each dimer binds to each half site present in a terminator site. The two half sites are termed A and B sites. Termination is observed to be blocked when the fork approaches the B site but not when it approaches the A site. However when B site was solely cloned into a vector, it could not effectively terminate replication, suggesting that induced polarity of RTP dimers on A and B site is required for termination (Smith and Wake 1992). Differential binding affinity model was proposed with the claim that the polarity is induced by binding of RTP dimers to each site with different strengths. It was hypothesised that the RTP dimer binding to the half site located in the "blocking" site binds tightly while the dimer binding to the "permissive" site binds less tightly to the site (Langly et al., 1993). However, after a series of experiments using mutant forms of terminator sites that contain RTP binding half sites with differential binding affinity, it was concluded that this differential binding affinity model cannot solely explain the polarity of termination(Duggin et al., 2005).
Structure
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Function
References
Langly, D.B., Smith, M.T., Lewis, P.J. and Wake, R.G. (1993). Protein-nucleoside contacts in the interaction between the replication terminator protein of Bacillus subtilis and the DNA terminator. Molecular Microbiology. 10(4):771-779.
Duggin, I.G., Matthews, J.M., Dixon, N.E., Wake, R.G. and Mackay, J.P. (2005). A complex mechanism determines polarity of DNA replication fork arrest by the replication terminator complex of Bacillus subtilis. J. Biol. Chem. 280(13):13105-13113.
Smith, M.T. and Wake, R.G. (1992). Definition and polarity of action of DNA replication terminators in Bacillus subtilis. J. Mol. Biol. 227(3):648-657.
