Lecture 4 - Transcription

Question 1

Sub-units of the E.Coli RNA polymerase “holoenzyme” (5)

Answer 1

α2ββ’ core

ω

α2ββ’σ holoenzyme

Question 2

α…

Answer 2

Is required for enzyme assembly (two copies per holoenzyme).

Question 3

β…

Answer 3

Forms a pincer with β’ that acts as a DNA clamp; target of rifampicin.

Question 4

β’… (3)

Answer 4

• Forms a pincer with β that acts as a DNA clamp.
• Provides a conserved NADFDGD motif essential for
  catalysis.
• The three aspartates in the motif co-ordinate Mg2+ and
  are essential for phosphodiester bond formation.

Question 5

ω…

Answer 5

Helps fold the β’ subunit before recruiting it to α2β.

Question 6

σ…

Answer 6

Is responsible for DNA binding specificity.