) Fig. 6.10, the blue curve suggests high level of transcription initiation for that set of samples. Why did it increase? Q1B) In the same figure, the data for the green curve was obtained with a so-called rifampicin-resistant core. You would expect that the green curve should overlap with the blue one, but it doesn’t. What is the reason?

Biochemistry
6th Edition
ISBN:9781305577206
Author:Reginald H. Garrett, Charles M. Grisham
Publisher:Reginald H. Garrett, Charles M. Grisham
Chapter29: Transcription And The Regulation Of Gene Expression
Section: Chapter Questions
Problem 16P
icon
Related questions
Topic Video
Question

Q1A) Fig. 6.10, the blue curve suggests high level of transcription initiation for that set of samples. Why did it increase?

Q1B) In the same figure, the data for the green curve was obtained with a so-called rifampicin-resistant core. You would expect that the green curve should overlap with the blue one, but it doesn’t. What is the reason?

RNA chain initiation
5.0
4.0
3.0
2.0
1.0
Add core
10
20
Time (min)
30
40
Figure 6.10 Sigma can be reused. Travers and Burgess allowed
RNA polymerase holoenzyme to initiate and elongate RNA chains on a
T4 DNA template at low ionic strength, so the polymerases could not
dissociate from the template to start new RNA chains. The red curve
shows the initiation of RNA chains, measured by [y-³2PJATP and
[y-³2P]GTP incorporation, under these conditions. After 10 min (arrow),
when most chain initiation had ceased, the investigators added new,
rifampicin-resistant core polymerase in the presence (green) or
absence (blue) of rifampicin. The immediate rise of both curves
showed that addition of core polymerase can restart RNA synthesis,
which implied that the new core associated with o that had been
associated with the original core. In other words, the σ was recycled.
The fact that transcription occurred even in the presence of rifampicin
showed that the new core, which was from rifampicin-resistant cells,
together with the old σ, which was from rifampicin-sensitive cells,
could carry out rifampicin-resistant transcription. Thus, the core, not
the σ, determines rifampicin resistance or sensitivity. (Source: Adapted
from Travers, A.A. and R.R. Burgess, "Cyclic re-use of the RNA polymerase sigma
factor." Nature 222:537-40, 1969.)
Transcribed Image Text:RNA chain initiation 5.0 4.0 3.0 2.0 1.0 Add core 10 20 Time (min) 30 40 Figure 6.10 Sigma can be reused. Travers and Burgess allowed RNA polymerase holoenzyme to initiate and elongate RNA chains on a T4 DNA template at low ionic strength, so the polymerases could not dissociate from the template to start new RNA chains. The red curve shows the initiation of RNA chains, measured by [y-³2PJATP and [y-³2P]GTP incorporation, under these conditions. After 10 min (arrow), when most chain initiation had ceased, the investigators added new, rifampicin-resistant core polymerase in the presence (green) or absence (blue) of rifampicin. The immediate rise of both curves showed that addition of core polymerase can restart RNA synthesis, which implied that the new core associated with o that had been associated with the original core. In other words, the σ was recycled. The fact that transcription occurred even in the presence of rifampicin showed that the new core, which was from rifampicin-resistant cells, together with the old σ, which was from rifampicin-sensitive cells, could carry out rifampicin-resistant transcription. Thus, the core, not the σ, determines rifampicin resistance or sensitivity. (Source: Adapted from Travers, A.A. and R.R. Burgess, "Cyclic re-use of the RNA polymerase sigma factor." Nature 222:537-40, 1969.)
Expert Solution
steps

Step by step

Solved in 3 steps

Blurred answer
Knowledge Booster
Gene expression
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
Biochemistry
Biochemistry
Biochemistry
ISBN:
9781305577206
Author:
Reginald H. Garrett, Charles M. Grisham
Publisher:
Cengage Learning
Biology 2e
Biology 2e
Biology
ISBN:
9781947172517
Author:
Matthew Douglas, Jung Choi, Mary Ann Clark
Publisher:
OpenStax