Regulation Of Transcription

Front 1

Enzyme encoded by lacZ gene

Back 1

Glucose and galactose products

Enzyme cleaves broad range of galactosides

Front 2

Structural genes of lac operon

Back 2

Encode for the primary structure of the enzymes/proteins

lac Z, lac Y, and lac A

Front 3

Lac I

Back 3

constitutive promoter and is expressed separately from the lac operon

Encodes lac repressor - low level of expression

Front 4

Holoenzyme

Back 4

RNA polymerase that can transcribe any gene that has a functional promoter

Front 5

Repressors

Back 5

Regulatory proteins that decrease the level of transcripts for certain genes

Front 6

Activators

Back 6

Proteins that increase transcription

Front 7

Regulatory sequences

Back 7

Specific DNA regions to which regulatory proteins bind (kb)

Front 8

Operator sites

Back 8

sequences recognized by regulators in bacteria

Front 9

Eukaryotic Vs Prokaryotic

Back 9

E. genes are more often controlled by distal regulatory sequences

Front 10

Locus control regions

Back 10

Found in more complex eukaryotes

Enhancer and insulator elements

Several proteins bind to and activate gene transcription

Front 11

DNA looping

Back 11

May bring the bound proteins to the promoter and encourage assembly of the transcription initiation complex

Front 12

Regulatory proteins

Back 12

Have a DNA binding domain that recognizes a specific sequence

Often modular

Aid in oligomerization

Activate or repress transcription

Interact with other regulators

Front 13

Allosteric effectors

Back 13

Small molecules that can bind directly to the regulatory proteins and change their conformation

Estrogen

Front 14

Helix turn helix

Back 14

common and found in many protein folds. First helix and recognition helix fits in the major groove

Many are dimers with the recognition helices spaced 3.4 nm apart to fit neighboring grooves

Front 15

Recognition helices

Back 15

In helix turn helix proteins read the DNA sequence through interactions with the base pairs

Homeodomain

Front 16

Homeodomain

Back 16

is a monomeric helix turn helix

Front 17

Zinc finger

Back 17

Prominent part of many DNA binding folds

Interacts with the two cysteines and two histidines

Insert its alpha helix into the minor groove

Most common DNA binding domains in the human genome

Front 18

Coiled-coils

Back 18

alpha helices that wind around each other form part of some DNA binding domains

Front 19

Basic region leucine zipper proteins

Back 19

have long alpha helices of about 60 amino acids

The two helices have hydrophobic leucing residues on the surfaces that "zip" together

Front 20

Basic region helix loop helix proteins

Back 20

Have a coiled coil and a helix that fits in the major groove

Have four helices joined by a loop. The region where the four helices interact is the Four Helix Bundle

Front 21

Immunoglobulins

Back 21

Made of beta sheets and connecting loops

Front 22

Trp repressor

Back 22

Helix turn helix protein

Depends on the level of tryptophan in the cell

When tryptophan levels are high, binds to operator and blocks RNA polymerase from binding

Front 23

RNA polymerase + promoter

Back 23

Activate transcription

Front 24

Catabolite activator protein

Back 24

Activates more than 100 E. coli promoters when carbon sources are low

Front 25

Glucose depletion

Back 25

Increases cAMP levels - this binds to CAP and increases its binding to DNA

Front 26

CAP

Back 26

enhances RNA polymerase by binding to the CTD

Class I: binds upstream of promoter

Class II: the CAP binding site overlaps the RNA polymerase binding site

Front 27

CAP and Lac I

Back 27

Regulate the lac operon

Front 28

Lac operon

Back 28

Responds to low glucose levels in the cell by allowing it to metabolize lactose instead if present

Front 29

In low glucose, lactose available

Back 29

CAP binds to the CAP operator, enhancing transcription STRONGLY ON

Front 30

In high glucose, lactose available

Back 30

Cap does not bind to the CAP operator, the lac repressor is not bound, WEAK transcription

Front 31

NtrC

Back 31

Activates genes that are important for nitrogen metabolism

Binds at enhancer elements and activates transcription when phosphorylated

Front 32

Oligomerization

Back 32

Stimulates its rate of ATP hydrolysis, which helps promote formation of the open complex