Nurturing Life Sciences
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#Unit 3. Fundamental Processes
Initiation relies solely upon the interaction between RNA polymerase and duplex DNA, however, the termination event also involves recognition of signals in the transcript by RNA polymerase.
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Rho factor is an essential protein in E. coli that causes transcription termination.
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The rho concentration may be as high as,10% the concentration of RNA polymerase. Rho-independent termination accounts for almost half of E. coli terminators.
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Rho binds to a sequence within the transcript upstream of the site of termination. This sequence is called a rut site (an acronym for rho utilization).
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When the RNA polymerase reaches the termination site, rho first freezes the structure of the polymerase and then invades the exit channel to destabilize the enzyme, causing it to release the RNA.
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Pausing by the polymerase at the site of termination allows time for rho factor to translocate to the hybrid stretch and is an important feature of termination.