Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding...

38
Transcrição I

Transcript of Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding...

Page 1: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

TranscriçãoI

Page 2: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Roteirodaaula

ü Transcriçãoemprocariotos

ü Operons

ü Regulação

Page 3: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Alberts,5thed

Page 4: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

DiferençasentreDNAeRNA

Lehninger,2nded

Page 5: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

EstruturasecundáriadoRNA

Alberts,5thed

Page 6: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Transcrição

Alberts,5thed Lehninger,2nded

Page 7: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Transcrição

Alberts,5thed

Page 8: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Direçãodatranscrição(E.coli)

Alberts,5thed

Page 9: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Transcrição–RNApolimerase

Alberts,5thed

Page 10: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

RNApolimerase

Alberts,5thed

Page 11: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

RNApolimerase

Alberts,5thed

Page 12: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

InteraçõesDNA-proteínas

Alberts,5thed

Page 13: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

RNApolimerasedeprocariotos

Lehninger,2nded

Page 14: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

RNApolimerasedeprocariotos

holoenzima

Lehninger,2nded

Page 15: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Transcriçãoemprocariotos

Alberts,5thed

Page 16: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Reconhecimentodepromotorespordiferentesfatoressigma(σ)

Alberts,5thed

Page 17: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Transcriçãoemprocariotos

•  Fatorσ:reconhecimentodediferentespromotores•  Distânciaentreoselementosregulatórios:importante

devidoageometriadaRNApolimerase

Regiãopromotora

Lehninger,2nded

Page 18: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Promotoresembactérias

Lehninger,2nded Alberts,5thed

Page 19: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Promotoresembactérias

AdaptadodeLewin,GenesVI

Page 20: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Bactériasvsvírus

Vírusproduzemfatorσsimilaraodebactérias

Alberts,5thed

Page 21: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Elongação

Lewin,GenesVI

Page 22: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Terminadoresemprocariotos

•  Intrínsecos:estruturasecundáriaRNA•  DependentesdofatorRho

Page 23: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Terminadoresemprocariotos

•  Intrínsecos

Lewin,GenesVI

Page 24: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Terminadoresemprocariotos

•  DependentedeRho

Lewin,GenesVI

Page 25: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Operon

•  TranscriçãodeumclusterdegenesaparKrdeumpromotorúnico

Alberts,5thed

Page 26: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Operontrp

Alberts,5thed

Page 27: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Operontrp

Alberts,5thed

Page 28: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Controledatranscriçãoemprocariotos:atenuação

(a) Two-component system regulating response to low Gin NtrB NtrC

Sensor domain High [G inl Ff®Dm cC

Regulatory domain c:;

His kinase transmitter domain

DNA-binding domain

Low [Ginl Sensor His kinase DNA-binding domain transmitter domain domain --· $ .._ ..L_ATP •

Gin enhancer

(b) General two-component signaling system Sensor Receiver domain domain

Histidine cC I kinase sensor

Sensor domain

His kinase domain

His kinase domain

1 Stimulus Effector domain

• .:Ibfa-C • L ATP G Effect?r

(a) trp leader RNA Translation start codon

Response

Response Regulator

FIGURE 7-5 Two-component regulatory systems. At low cytoplasmic concentrations of glutamine, glutamine dissociates from NtrB, resulting in a conformational change that activates a protein kinase transmitter domain that transfers an ATP "(·phosphate to a conserved histidine (H) in the transmitter domain. This phosphate is then transferred to an aspartic acid (D) in the regulatory domain of the response regulator NtrC. This converts Ntrc into its activated form, which binds the enhancer sites upstream of the ginA promoter (Figure 7-4). (b) General organization of two-component histidyl-aspartyl phospho-relay regulatory systems in bacteria and plants. [Adapted from A. H. West and A.M. Stock, 2001, Trends Biochem. Sci. 26:369.]

its synthesis or for the translation of the encoded proteins when the concentration of tryptophan is high.

However, when the concentration of tRNArrp is not suffi-cient to support a high rate of protein synthesis, the ribosome stalls at the rwo successive Trp codons in region 1 (Figure 7-6b, right). As a consequence, region 2 base-pairs with region 3 as soon as it emerges from the transcribing RNA polymerase. This prevents region 3 from base-pairing with region 4, so the 3-4 hairpin does not form and does not cause pausing by RNA polymerase or transcription termination. As a result, the pro-teins required for tryptophan synthesis are translated by ribo-somes that initiate translation at the start codons for each of these proteins in the long polycistronic Trp mRNA.

Attenuation of transcription elongation also occurs at some operons and single genes encoding enzymes involved in the biosynthes is of other amino acids and metabolites through the function of riboswitches. Riboswitches form RNA tertiary structures that can bind small molecules when they are present at sufficiently high concentration. In some

1 w 100

s·l.....-..!...------t==r.::=J--c:cr--.J....-cx :r-c=:!:::J uuuuul3·

(b) Translation of trp leader

High tryptophan Ribosome covers region 2

5' transcription

UUUUU 3'

FIGURE 7-6 Transcription control by regulation of RNA polymerase elongation and termination in the E. coli Trp operon. (a) Diagram of the 140-nucleotide trp leader RNA. Colored regions are critical to the control of attenuation. (b) Translation of the trp leader sequence begins from the 5' end soon after it is synthesized, while synthesis of the rest of the polycistronic trp mRNA molecule continues.

Low tryptophan Ribosome is stalled at trp codons in region 1

5'

2-3 stem-loop forms

RNA polymerase continues transcription

At high concentrations of amino-acylated tRNA1'P, formation of the 3-4 stem-loop followed by a series of Us causes termination of transcrip-tion. At low amino-acylated tRNA1 'P, region 3 is sequestered in the 2-3 stem-loop and cannot base-pair with region 4. In the absence of the stem-loop structure required for termination, transcription of the trp operon continues. [See C Yanofsky, 1981, Nature 289:751 .]

7.1 Control of Gene Expression in Bacteria 287

Nãocodificaenzimas– sequêncialídercodificandoparaTrp

Alberts,5thedLodisch,7thed

Page 29: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Controledatranscriçãoemprocariotos:atenuação

(a) Two-component system regulating response to low Gin NtrB NtrC

Sensor domain High [G inl Ff®Dm cC

Regulatory domain c:;

His kinase transmitter domain

DNA-binding domain

Low [Ginl Sensor His kinase DNA-binding domain transmitter domain domain --· $ .._ ..L_ATP •

Gin enhancer

(b) General two-component signaling system Sensor Receiver domain domain

Histidine cC I kinase sensor

Sensor domain

His kinase domain

His kinase domain

1 Stimulus Effector domain

• .:Ibfa-C • L ATP G Effect?r

(a) trp leader RNA Translation start codon

Response

Response Regulator

FIGURE 7-5 Two-component regulatory systems. At low cytoplasmic concentrations of glutamine, glutamine dissociates from NtrB, resulting in a conformational change that activates a protein kinase transmitter domain that transfers an ATP "(·phosphate to a conserved histidine (H) in the transmitter domain. This phosphate is then transferred to an aspartic acid (D) in the regulatory domain of the response regulator NtrC. This converts Ntrc into its activated form, which binds the enhancer sites upstream of the ginA promoter (Figure 7-4). (b) General organization of two-component histidyl-aspartyl phospho-relay regulatory systems in bacteria and plants. [Adapted from A. H. West and A.M. Stock, 2001, Trends Biochem. Sci. 26:369.]

its synthesis or for the translation of the encoded proteins when the concentration of tryptophan is high.

However, when the concentration of tRNArrp is not suffi-cient to support a high rate of protein synthesis, the ribosome stalls at the rwo successive Trp codons in region 1 (Figure 7-6b, right). As a consequence, region 2 base-pairs with region 3 as soon as it emerges from the transcribing RNA polymerase. This prevents region 3 from base-pairing with region 4, so the 3-4 hairpin does not form and does not cause pausing by RNA polymerase or transcription termination. As a result, the pro-teins required for tryptophan synthesis are translated by ribo-somes that initiate translation at the start codons for each of these proteins in the long polycistronic Trp mRNA.

Attenuation of transcription elongation also occurs at some operons and single genes encoding enzymes involved in the biosynthes is of other amino acids and metabolites through the function of riboswitches. Riboswitches form RNA tertiary structures that can bind small molecules when they are present at sufficiently high concentration. In some

1 w 100

s·l.....-..!...------t==r.::=J--c:cr--.J....-cx :r-c=:!:::J uuuuul3·

(b) Translation of trp leader

High tryptophan Ribosome covers region 2

5' transcription

UUUUU 3'

FIGURE 7-6 Transcription control by regulation of RNA polymerase elongation and termination in the E. coli Trp operon. (a) Diagram of the 140-nucleotide trp leader RNA. Colored regions are critical to the control of attenuation. (b) Translation of the trp leader sequence begins from the 5' end soon after it is synthesized, while synthesis of the rest of the polycistronic trp mRNA molecule continues.

Low tryptophan Ribosome is stalled at trp codons in region 1

5'

2-3 stem-loop forms

RNA polymerase continues transcription

At high concentrations of amino-acylated tRNA1'P, formation of the 3-4 stem-loop followed by a series of Us causes termination of transcrip-tion. At low amino-acylated tRNA1 'P, region 3 is sequestered in the 2-3 stem-loop and cannot base-pair with region 4. In the absence of the stem-loop structure required for termination, transcription of the trp operon continues. [See C Yanofsky, 1981, Nature 289:751 .]

7.1 Control of Gene Expression in Bacteria 287

RibossomoparaporquenãoencontratRNATrp!

Lodisch,7thed

Page 30: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Operonlac

GlicosexLactose:bactériausaprimeiroaglicose

Alberts,5thed

Page 31: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Operonlac

Alberts,5thed

Page 32: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Operonlac

Alberts,5thed

Page 33: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Reguladoresdatranscrição

Alberts,5thed

Page 34: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Reguladoresdatranscrição

Alberts,5thed

Page 35: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

(a) Two-component system regulating response to low Gin NtrB NtrC

Sensor domain High [G inl Ff®Dm cC

Regulatory domain c:;

His kinase transmitter domain

DNA-binding domain

Low [Ginl Sensor His kinase DNA-binding domain transmitter domain domain --· $ .._ ..L_ATP •

Gin enhancer

(b) General two-component signaling system Sensor Receiver domain domain

Histidine cC I kinase sensor

Sensor domain

His kinase domain

His kinase domain

1 Stimulus Effector domain

• .:Ibfa-C • L ATP G Effect?r

(a) trp leader RNA Translation start codon

Response

Response Regulator

FIGURE 7-5 Two-component regulatory systems. At low cytoplasmic concentrations of glutamine, glutamine dissociates from NtrB, resulting in a conformational change that activates a protein kinase transmitter domain that transfers an ATP "(·phosphate to a conserved histidine (H) in the transmitter domain. This phosphate is then transferred to an aspartic acid (D) in the regulatory domain of the response regulator NtrC. This converts Ntrc into its activated form, which binds the enhancer sites upstream of the ginA promoter (Figure 7-4). (b) General organization of two-component histidyl-aspartyl phospho-relay regulatory systems in bacteria and plants. [Adapted from A. H. West and A.M. Stock, 2001, Trends Biochem. Sci. 26:369.]

its synthesis or for the translation of the encoded proteins when the concentration of tryptophan is high.

However, when the concentration of tRNArrp is not suffi-cient to support a high rate of protein synthesis, the ribosome stalls at the rwo successive Trp codons in region 1 (Figure 7-6b, right). As a consequence, region 2 base-pairs with region 3 as soon as it emerges from the transcribing RNA polymerase. This prevents region 3 from base-pairing with region 4, so the 3-4 hairpin does not form and does not cause pausing by RNA polymerase or transcription termination. As a result, the pro-teins required for tryptophan synthesis are translated by ribo-somes that initiate translation at the start codons for each of these proteins in the long polycistronic Trp mRNA.

Attenuation of transcription elongation also occurs at some operons and single genes encoding enzymes involved in the biosynthes is of other amino acids and metabolites through the function of riboswitches. Riboswitches form RNA tertiary structures that can bind small molecules when they are present at sufficiently high concentration. In some

1 w 100

s·l.....-..!...------t==r.::=J--c:cr--.J....-cx :r-c=:!:::J uuuuul3·

(b) Translation of trp leader

High tryptophan Ribosome covers region 2

5' transcription

UUUUU 3'

FIGURE 7-6 Transcription control by regulation of RNA polymerase elongation and termination in the E. coli Trp operon. (a) Diagram of the 140-nucleotide trp leader RNA. Colored regions are critical to the control of attenuation. (b) Translation of the trp leader sequence begins from the 5' end soon after it is synthesized, while synthesis of the rest of the polycistronic trp mRNA molecule continues.

Low tryptophan Ribosome is stalled at trp codons in region 1

5'

2-3 stem-loop forms

RNA polymerase continues transcription

At high concentrations of amino-acylated tRNA1'P, formation of the 3-4 stem-loop followed by a series of Us causes termination of transcrip-tion. At low amino-acylated tRNA1 'P, region 3 is sequestered in the 2-3 stem-loop and cannot base-pair with region 4. In the absence of the stem-loop structure required for termination, transcription of the trp operon continues. [See C Yanofsky, 1981, Nature 289:751 .]

7.1 Control of Gene Expression in Bacteria 287

Reguladoresdatranscrição

Lodisch,7thed

Page 36: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Reguladoresdatranscrição

NtrCaKvatranscriçãoadistância

Alberts,5thed

Page 37: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Rifampicinabloqueiatranscrição

Desenvolvimentodefármacos– processosprocarióKcoseeucarióKcos

Page 38: Transcrição I - coltri.bio.br · Transcrição em procariotos ... Sensor His kinase DNA-binding --domain transmitter · domain domain $ .._ ..L_ATP • Gin enhancer (b) General

Parasabermais

•  MolecularBiologyoftheCell–Albertsetal•  GenesVI–Lewin•  PrinciplesofBiochemistry– Lehninger•  MolecularCellBiology-Lodisch