Elementary plant Biochemistry and Biotechnology (2+1)

Termination and release of new RNA

• Termination of RNA synthesis occurs at specific base sequences within the DNA molecule. These sequences are of two types, simple terminators and those that require auxiliary termination factors. At a particular sequence, if there is an inverted repeat containing a central nonrepeating segment, ie., the sequence in one DNA strand would read like TATAT- NNN – ATATA, then the RNA transcribed from this strand form a intrastrand base paring and leads to stem and loop structure. Termination occurs at this hairpin region for unknown reasons.


• Alternatively, termination also occurs due to auxiliary termination protein called – Rho protein. It binds tightly with RNA which has segment that are rich in C (especially repeating C’s). The binding helps the protein to acquire a powerful ATP cleaving activity that is essential to its action in termination. This is because, nucleoside triphosphates cannot reach RNA polymerase since they are degraded by Rho protein. Significant differences exist between the structures and modes of synthesis of the RNA molecules of prokaryotes and eukaryotes, though the basic mechanisms of their functions are nearly the same.