Question

We know that region 2.4 of sigma factor binds DNA at -10box. What is the function of 2.1?

(a) It is a flexible loop with no known function

(b) It binds -35box

(c) It binds RNA polymerase

(d) It binds region 4.1 to give sigma its specific structure and function

I had been asked this question in an interview.

My question is taken from Transcription in Prokaryotes : Sigma Factor topic in section Gene Expression : Transcription Prokaryotes of Cytogenetics

Answer 1

Right choice is (c) It binds RNA polymerase

The explanation: Region 2.1 helps to bind the sigma factor to the RNA polymerase. The binding is not absolute as this factor is dissociable. -35box on the other hand is recognized by region 4.2.