Question

Which is the "Only enzyme" that has "Capability" to catalyse initiation, elongation and termination in the process of transcription in prokaryotes?

Answer 1

Transcription is the process of copying genetic information from one strand of the DNA (template strand) into RNA.

It occurs in three steps: initiation, elongation and termination.

The enzyme DNA dependent RNA polymerase is capable of catalysing all the three steps of transcription in prokaryotes.

For initiation of transcription, the sigma factor of RNA polymerase is required. It is also called the specificity factor. Sigma factors provide promoter recognition specificity to the RNA polymerase and contribute to DNA strand separation. They then dissociate from the RNA polymerase enzyme following transcription initiation.

During the elongation step, the RNA polymerase uses nucleoside triphosphates as substrate and polymerises in a template-dependent way following the rule of complementarity.

Once the RNA polymerase reaches the terminator region of the transcription unit, the rho factor encounters RNA polymerase. Rho (ρ) is an ATP-dependent RNA-stimulated helicase that disrupts the initial RNA-DNA complex and hence serves as a transcription termination factor. This results in termination of transcription. The nascent RNA ultimately falls off.

DNase is an enzyme that catalyzes the cleavage of phosphodiester linkages in the DNA.

DNA-dependent DNA polymerase is responsible for directing the synthesis of new DNA.

DNA ligase facilitates the joining of DNA strands together.