12 Regulation of Gene Expression

Transcription

1 FIND HP TO ox Helix 1 12 Helix 2: recognition 20 mino acids Helix Turn Helix Helix 1 Helix 2

2 FIND HP TO Figure 12.1 Merodiploid Phenotype Interpretation F lac lac m2 m1 1. Lac + 2. Lac omplementation; m1 and m2 are in different genes No complementation; m1 and m2 are in the same gene

3 FIND HP TO Figure 12.2 Merodiploid Phenotype Interpretation F I + lac p + Y + O + Z + or Lac No complementation; the cis-acting lacp mutation prevents expression of lacz, lacy, and lac I + p + O + Z Y + lac

4 FIND HP TO Merodiploid Phenotype Interpretation Figure 12.3 laci p + O + F Z + I + Y + Lac + inducible laci is recessive laci + p + O + Z + Y + + laci + p + O c F ON Z + I Lac constitutive laco c is dominant and cis acting + Y + laci + p + O + Z + Y + +

5 FIND HP TO Table 12.1

6 FIND HP TO bsence of lactose laci LacI lacp laco lacz OFF lacy Figure 12.4 lac Presence of lactose laci lacp laco N Pol lacz lacy lac LacI ON llolactose

7 FIND HP TO Figure 12.5 lacp o 3 82 o o TTTT 10 o 3 o 1

8 FIND HP TO Figure 12.6 N polymerase interaction region P-binding site epressor-binding site TTT TTGTT TGGTTGGTTTTTTGGTGGTTG TGGGGTG TGT GTGGGGG T T TTGTTTGTTGTGTGTTTTGTGTTGGT Stop 35 region 10 region +1 fmet Thr Met mn start site laci p o 1 lacz epressor coding region Promoter Operator +20 β-galactosidase coding region

9 FIND HP TO Figure 12.7 epressor gal p G2 p G1 gale galt galk o E o I ( ) cmp P (+)

10 FIND HP TO Galactose + TP galactose-1-po 4 GalK Figure 12.8 Galactose-1-PO 4 + UDPglucose GalT UDPgalactose + glucose UDPgalactose GalE UDPglucose UTP + glucose-1-po 4 GalU UDPglucose

11 FIND HP TO Figure 12.9 epressor gal epressor gal epressor gal Multicopy plasmid with o E Multicopy plasmid with o E and o I

12 FIND HP TO Figure Multiple of 10 bp p 2 p 1 o E epressors bound to same side of helix o I p 2 p 1 o E Multiple of 15 bp p 2 p 1 o I

13 FIND HP TO p 2 Figure p 1 o E gale o I o E o I HU Gal

14 FIND HP TO Figure p trp trpl trpe trpd trp trp trp ter trp mn Leader polypeptide nthranilate synthetase Indole glycerolphosphate synthetase Tryptophan synthetase horismic acid anthranilic acid P DP InGP tryptophan

15 FIND HP TO Figure In the absence of tryptophan p trp O L trpe D trp mn ON epressor In the presence of tryptophan p trp O L E D OFF trp

16 FIND HP TO Figure porepressor dimer Helix 1 Helix-turn-helix domain: Helix 2 D E F N N E D F porepressor - repressor conformational change porepressor HTH (D + E) D E Trp corepressor NH 3 H 2 H OO epressor HTH (D + E) E D

17 FIND HP TO Figure ra P site ara p p D ara ara arad arao 2 arao 1 arai L-ibulose kinase L-rabinose isomerase L-ibulose-5- P epimerase L-rabinose L-ribulose L-ribulose-5- phosphate D-xylulose-5- phosphate P1 rabinose P2 ra ra ra ra ntiactivator rabinose ctivator

18 FIND HP TO Figure bsence of arabinose F OFF D P2 + O I OFF P1 P1 form binds to operators of both operons, preventing arad expression c O I D Presence of arabinose + F ON O I D P2 ON P2 rabinose P2 form and/or the ra c (=P2) form binds to I (induction) sites of both operons, activating arad transcription c O I D

19 FIND HP TO bsence of L-arabinose 200 arao ra Figure p ra p D OFF arao I 1 I 2 arai Presence of L-arabinose ON ara p ra ra p D I 1 I arai ON N Pol arad mn OFF ra p arao 1

20 FIND HP TO Figure Maltotriose + T activates ON 75 min malq malp malt egulation 91 min malg malf male malk Iam malm Maltose uptake Maltose uptake mylomaltose phosphorylase ON ON 36 min mali malx maly 80 min mals α-mylase represses I

21 FIND HP TO Maltodextrins Figure MalS Lam MalE Outer membrane Periplasmic space MalF MalG MalK T T MalK Maltose, Maltodextrins MalP MalQ ytoplasmic membrane Glucose-6-phosphate

22 FIND HP TO XylS Figure p U xyl M N p L xylx p Y Z LT EG F Q K I H xyls xyl Upper pathway Lower pathway p S Xyl H 3 Toluene OOH enzoate OOH enzoate T cycle

23 FIND HP TO ox 12.3

24 FIND HP TO ntiterminator structure 2:3 Figure eadthrough conformation UG T T UG 1 4 lternative N secondary structures of the leader transcript Leader peptide coding region Pause structure G 1:2 U T T 1 2 Pause hairpin Terminator hairpin structure 3 3:4 4 Termination conformation N UG UUUUUUU DN Promoter Transcription start TG T T Leader peptide coding region TG Pause site ttenuator First structural gene

25 FIND HP TO Figure N Pol pauses at 1:2 pause site ibosome initiates fmet Lys ibosome releases paused N Pol 5 ' ppp N 26 UGGUUUU GUUGGGUU UG G G U G G U U G G U U 1 G 2 U U G G U G G D ttenuation in presence of Trp trpl Trp Trp rg ibosome Ser Thr rg Trp Met Lys la IlePhe Val Leu Lys Gly Trp Stop Transcription elongation in absence of Trp 2 U G U U U U G U G U G G U N Pol G G 3 G 4 G G G G U G 140 UUU U U U Structural genes egions 3 and 4 form a terminator hairpin N Pol terminates +1 trpl N Pol 140 G GUUUU U U Structural genes 4 Lack of trp tn causes ribosome to stall Gly Lys Leu Val Phe Ile la Lys Met Trp Trp rg 2 G GG 3 G U G U U U U G U G U U U G G G egions 2 and 3 base pair, preventing 3 and 4 from forming a terminator hairpin U