Regulation of Gene Expression in Bacteria and Their Viruses CHAPTER 10 Regulation of Gene Expression in Bacteria and Their Viruses Copyright 2008 © W H Freeman and Company

CHAPTER OUTLINE 10.1 Gene regulation 10.2 Discovery of the lac system: negative control 10.3 Catabolite repression of the lac operon: positive control 10.4 Dual positive and negative control: the arabinose operon 10.5 Metabolic pathways and additional levels of regulation: attenuation 10.6 Bacteriophage life cycles: more regulators, complex operons 10.7 Alternative sigma factors regulate large sets of genes

Regulatory proteins control transcription Figure 10-2

Allosteric effectors bind to regulatory proteins Figure 10-3

Repressor protein controls the lac operon Figure 10-4

Lactose is broken down into two sugars Figure 10-5

The lac operon is transcribed only in the presence of lactose Figure 10-6a

The lac operon is transcribed only in the presence of lactose Figure 10-6b

Structure of IPTG Figure 10-7

Table 10-1

Operators are cis-acting Figure 10-8

Table 10-2

Repressors are trans-acting Figure 10-9

Table 10-3

The repressor contains a lactose-binding site Figure 10-10

RNA polymerase contacts the promoter at specific sequences Figure 10-11

The operator is a specific DNA sequence Figure 10-12

Glucose levels control the lac operon Figure 10-13

Glucose levels control the lac operon Figure 10-13a

Glucose levels control the lac operon Figure 10-13b

Many DNA binding sites are symmetrical Figure 10-14

Binding of CAP bends DNA Figure 10-15

CAP and RNA polymerase bind next to each other Figure 10-16

Negative and positive control of the lac operon Figure 10-17

Negative and positive control of the lac operon Figure 10-17a

Negative and positive control of the lac operon Figure 10-17b

Negative and positive control of the lac operon Figure 10-17c

Repression and activation compared Figure 10-18

Repression and activation compared Figure 10-18a

Repression and activation compared Figure 10-18b

Map of the ara operon Figure 10-19

AraC serves as an activator and as a repressor Figure 10-20

Gene order in the trp operon corresponds to reaction order in the biosynthetic pathway Figure 10-21

The trp mRNA leader sequence contains an attenuator region and two tryptophan codons Figure 10-22

Abundant tryptophan attenuates transcription of the trp operon Figure 10-23

Leader peptides of amino acid biosynthesis operons Figure 10-24

The life cycle of bacteriophage  Figure 10-25

Phage  genome is organized for coordinate control Figure 10-26

The lysogenic-versus-lytic cycle is determined by repressor occupancy on the OR operators Figure 10-27

Helix-turn-helix is a common DNA-binding motif Figure 10-28

Amino acid side chains determine the specificity of DNA binding Figure 10-29

 factors control clusters of unlinked genes Figure 10-30a

 factors control clusters of unlinked genes Figure 10-30b