Question

in E.coli rho factor is required for

Answer 1

Answer:

termination process.

Explanation:

The interaction of E. coli termination factor rho with the nascent RNA transcript appears to be a central feature of the rho-dependent transcription termination process.

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Answer 2

Answer:

Rho factor is important for the viability of the cell as it is required to perform factor-dependent transcription termination by RNA polymerase.

Explanation:

Rho factor in Escherichia coli or E.coli is a homohexameric protein that recognizes and binds to the C-rich sites present in the transcribed RNA.

It utilizes RNA-dependent ATPase activity and later on ATPase- dependent helicase activity to release RNA from a transcribing elongation complex by unwinding RNA-DNA hybrids.

There are 2 kinds of terminations that occur in the genome of E.coli.

• First is without the use of auxiliary proteins - in which GC rich inverted repeat sequence and thymidylate are involved.

• 2nd is factor-dependent termination- in which the Rho factor is involved.

Rho terminates the transcription process in response to specific DNA signals transcribed into RNA known as rho-dependent terminators.

2 essential features of the Rho-dependent terminator are-

• rut site or a proximal Rho binding site or Rho utilization site. It contains 70 to 80 nucleotides rich in cytosine.
• Termination zone or the distal sequence.

Rho-dependent termination of transcription in E.coli is explained in the following steps-

• It binds to the naked (non-translating) RNA at a C-rich site called the Rho utilization site or rut site. N-terminal or primary binding domain helps in this binding.

• Through the primary binding site, the now bound RNA reaches the secondary binding site which is present on the C-terminal.

• Rho is stimulated for ATP hydrolysis at RNA-bound secondary sites.

• ATP hydrolysis releases the energy which is used in the unwinding of RNA/DNA duplex or RNA-DNA hybrid by powering the translocase/helicase activity of Rho.