LM7 - Regulationofmacromolecularprocesses 1...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Regulation of macromolecular processes 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Overview of regulation • Replication – ATP levels (DnaA) – Regulation by SeqA/GATC methylation at oriC • Transcription – Usually regulated at initiation  (activators/repressors) – Attenuation affects premature termination 2
Background image of page 2
Overview of regulation cont. • Translation – Usually regulated at initiation by riboswitch  (via SD occlusion or attenuation) or sRNA • Post-translational control of enzymatic  activity – Covalent modification – Allosteric control by ligands  3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Negative regulation of transcription (Fig. 13.3) • Negative regulation of  transcription is carried out  by DNA-binding proteins  called repressors (a,b) • Repressors bind to  operators (DNA sites) and  interfere with RNAP  activity • Repressors act by  preventing either initiation  or elongation of  transcription 4
Background image of page 4
More negative regulation of transcription (Fig. 13.3) • Co-repressors and  inducers are ligands  that bind to repressors  to regulate repressor  activity (i.e., the  ability to bind to their  operators) under  different conditions • Co-repressors (b) are  used for genes involved  in anabolic reactions,  and inducers (a) are  used for catabolic  reaction genes 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Positive regulation of transcription (Fig. 13.3c) • Positive regulation of  transcription is carried out  by DNA-binding proteins  called activators • Genes positively regulated  are only transcribed  when  activators bind to DNA and  facilitate RNAP activity at  promoters • Activators act by helping  RNAP or other activators to  bind at promoters • Activators bind  ligands   that regulate DNA-binding  activity under different  conditions 6
Background image of page 6
Transcriptional regulatory strategies (Fig. 13.4) • Catabolic pathways use repressors and inducers (signals  that substrates are present) + positive control • Biosynthetic pathways use repressors and co-repressors  (end product is often the co-repressor, when present) • Biosynthetic pathways also use other transcriptional  controls (e.g., attenuation) and also translational and  post-translational (regulation of activity) controls 7
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The  lac  operon in  E. coli  (Figs. 13.2, 13.5) • The  lac  operon gene products control entry and catabolism of  lactose (lac) as an alternate energy source when the  preferred sugar glucose (glc) is unavailable • CAP is a positive regulator that is activated by binding to  cAMP when glc levels are low • CAP-cAMP binds just upstream of the promoter and  stimulates binding of RNAP (this promoter doesn’t readily  bind to RNAP in absence of CAP-cAMP) 8
Background image of page 8
More regulation of  lac  operon in  E. coli  (Fig. 13.7) Lac I gene encodes repressor that  binds to the operator ( in the 
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 31

LM7 - Regulationofmacromolecularprocesses 1...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online