User:David Jung/BCHM3981 RTP Tus
From Proteopedia
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'''The Replication Terminator Protein (RTP)''' is a protein involved in termination of replication in the gram positive bacterium, ''Bacillus subtilis''. RTP was first identified in 1989, showing analogous function to Tus protein present in ''Escherichia coli'' (Lewis, Smith and Wake, 1989). Both RTP and Tus bind to termination sites (''Ter'' sequences) present in the bacterial chromosome, terminating replication. Polar directionality of termination is assumed as circular bacterial chromosome is replicated bidirectionally with one replication fork going one way and the other one going the other way. RTP-''Ter'' complex must therefore terminate replication when a fork comes from one side and permit a fork that comes from the other side. | '''The Replication Terminator Protein (RTP)''' is a protein involved in termination of replication in the gram positive bacterium, ''Bacillus subtilis''. RTP was first identified in 1989, showing analogous function to Tus protein present in ''Escherichia coli'' (Lewis, Smith and Wake, 1989). Both RTP and Tus bind to termination sites (''Ter'' sequences) present in the bacterial chromosome, terminating replication. Polar directionality of termination is assumed as circular bacterial chromosome is replicated bidirectionally with one replication fork going one way and the other one going the other way. RTP-''Ter'' complex must therefore terminate replication when a fork comes from one side and permit a fork that comes from the other side. | ||
| - | [[Image:RTP.jpg | thumb]] | + | [[Image:RTP.jpg | thumb|altA= It shows RTP binding to terminations replication site. |RTP binding to dsDNA molecule]] |
== History == | == History == | ||
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== Function == | == Function == | ||
RTP is involved in replication termination. | RTP is involved in replication termination. | ||
| - | [[Image:Bacillus_ter.jpg |thumb|left]] | + | [[Image:Bacillus_ter.jpg |thumb|left|none|altA= It shows ''ter'' sites within the bacterial chromosome.|Replication termination sites in ''Bacillus subtilis'']] |
== References == | == References == | ||
Revision as of 00:41, 20 May 2011
The Replication Terminator Protein (RTP) is a protein involved in termination of replication in the gram positive bacterium, Bacillus subtilis. RTP was first identified in 1989, showing analogous function to Tus protein present in Escherichia coli (Lewis, Smith and Wake, 1989). Both RTP and Tus bind to termination sites (Ter sequences) present in the bacterial chromosome, terminating replication. Polar directionality of termination is assumed as circular bacterial chromosome is replicated bidirectionally with one replication fork going one way and the other one going the other way. RTP-Ter complex must therefore terminate replication when a fork comes from one side and permit a fork that comes from the other side.
Contents |
History
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
RTP is classified as a winged helix-loop-helix protein.
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Function
RTP is involved in replication termination.
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.
Lewis, P.J., Smith, M.T. and Wake, R.G. (1989). A protein involved in termination of chromosome replication in Bacillus subtilis binds specifically to the terC site. J. Bacteriology. 171(6):3564-3567.
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.
