A model for transcription termination suggested by studies on the trp attenuator in vitro using base analogs

P. J. Farnham, T. Platt

Research output: Chapter in Book/Report/Conference proceedingChapter

74 Citations (Scopus)

Abstract

In vitro termination of transcription at the attenuator site of the E. coli tryptophan (trp) operon occurs efficiently in the absence of additional factors. In contrast, an altered attenuator site created by the deletion trpΔLC1419 (which removes four of the eight consecutive TA base pairs at the termination site, but still functions partially in vivo) does not cause termination in vitro under standard conditions, even with the addition of rho factor. By varying components and conditions to the transcription reactions, we have found conditions under which termination does occur at the altered site (trp a1419), as well as conditions affecting termination on the wild-type template. RNA polymerase can terminate at trp a1419 when the analog iodo-CTP (which forms stronger base pairs with G) replaces CTP. A mutant polymerase (rpo203) that restores termination in strains carrying rho mutations can also terminate at trp a1419 at a position just past the deletion junction, suggesting that the point of termination may be specified by the remaining upstream leader sequence. Analogs such as Br-UTP and allylamine-UTP, which form stronger base pairs with A, elevate readthrough levels at the wild-type attenuator site. At low temperatures, readthrough on the wild-type template by wild-type RNA polymerase is enhanced, whereas the rpo203 enzyme still terminates efficiently. The results of these experiments suggest a model for termination of transcription in the absence of rho factor involving both RNA-RNA and RNA-DNA interactions. We propose that the response of RNA polymerase at a terminator site is governed by a balance between the formation or stability of a hairpin structure in the transcript and the strength of polymerase-stabilized base pairing between the distal nucleotides of the transcript and the DNA template. In more complex cases in vitro, or within the cell, formation or stabilization of these structures may also involve other regions of RNA and additional factors.

Original languageEnglish (US)
Title of host publicationCell
Pages739-748
Number of pages10
Volume20
Edition3
StatePublished - 1980
Externally publishedYes

Fingerprint

Tryptophan
Base Pairing
Rho Factor
DNA-Directed RNA Polymerases
RNA
Cytidine Triphosphate
Uridine Triphosphate
Allylamine
DNA
Operon
Nucleotides
Escherichia coli
Mutation
Temperature
In Vitro Techniques
Enzymes

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Farnham, P. J., & Platt, T. (1980). A model for transcription termination suggested by studies on the trp attenuator in vitro using base analogs. In Cell (3 ed., Vol. 20, pp. 739-748)

A model for transcription termination suggested by studies on the trp attenuator in vitro using base analogs. / Farnham, P. J.; Platt, T.

Cell. Vol. 20 3. ed. 1980. p. 739-748.

Research output: Chapter in Book/Report/Conference proceedingChapter

@inbook{38554bfe02314fe580e7c0a3c5788cc3,
title = "A model for transcription termination suggested by studies on the trp attenuator in vitro using base analogs",
abstract = "In vitro termination of transcription at the attenuator site of the E. coli tryptophan (trp) operon occurs efficiently in the absence of additional factors. In contrast, an altered attenuator site created by the deletion trpΔLC1419 (which removes four of the eight consecutive TA base pairs at the termination site, but still functions partially in vivo) does not cause termination in vitro under standard conditions, even with the addition of rho factor. By varying components and conditions to the transcription reactions, we have found conditions under which termination does occur at the altered site (trp a1419), as well as conditions affecting termination on the wild-type template. RNA polymerase can terminate at trp a1419 when the analog iodo-CTP (which forms stronger base pairs with G) replaces CTP. A mutant polymerase (rpo203) that restores termination in strains carrying rho mutations can also terminate at trp a1419 at a position just past the deletion junction, suggesting that the point of termination may be specified by the remaining upstream leader sequence. Analogs such as Br-UTP and allylamine-UTP, which form stronger base pairs with A, elevate readthrough levels at the wild-type attenuator site. At low temperatures, readthrough on the wild-type template by wild-type RNA polymerase is enhanced, whereas the rpo203 enzyme still terminates efficiently. The results of these experiments suggest a model for termination of transcription in the absence of rho factor involving both RNA-RNA and RNA-DNA interactions. We propose that the response of RNA polymerase at a terminator site is governed by a balance between the formation or stability of a hairpin structure in the transcript and the strength of polymerase-stabilized base pairing between the distal nucleotides of the transcript and the DNA template. In more complex cases in vitro, or within the cell, formation or stabilization of these structures may also involve other regions of RNA and additional factors.",
author = "Farnham, {P. J.} and T. Platt",
year = "1980",
language = "English (US)",
volume = "20",
pages = "739--748",
booktitle = "Cell",
edition = "3",

}

TY - CHAP

T1 - A model for transcription termination suggested by studies on the trp attenuator in vitro using base analogs

AU - Farnham, P. J.

AU - Platt, T.

PY - 1980

Y1 - 1980

N2 - In vitro termination of transcription at the attenuator site of the E. coli tryptophan (trp) operon occurs efficiently in the absence of additional factors. In contrast, an altered attenuator site created by the deletion trpΔLC1419 (which removes four of the eight consecutive TA base pairs at the termination site, but still functions partially in vivo) does not cause termination in vitro under standard conditions, even with the addition of rho factor. By varying components and conditions to the transcription reactions, we have found conditions under which termination does occur at the altered site (trp a1419), as well as conditions affecting termination on the wild-type template. RNA polymerase can terminate at trp a1419 when the analog iodo-CTP (which forms stronger base pairs with G) replaces CTP. A mutant polymerase (rpo203) that restores termination in strains carrying rho mutations can also terminate at trp a1419 at a position just past the deletion junction, suggesting that the point of termination may be specified by the remaining upstream leader sequence. Analogs such as Br-UTP and allylamine-UTP, which form stronger base pairs with A, elevate readthrough levels at the wild-type attenuator site. At low temperatures, readthrough on the wild-type template by wild-type RNA polymerase is enhanced, whereas the rpo203 enzyme still terminates efficiently. The results of these experiments suggest a model for termination of transcription in the absence of rho factor involving both RNA-RNA and RNA-DNA interactions. We propose that the response of RNA polymerase at a terminator site is governed by a balance between the formation or stability of a hairpin structure in the transcript and the strength of polymerase-stabilized base pairing between the distal nucleotides of the transcript and the DNA template. In more complex cases in vitro, or within the cell, formation or stabilization of these structures may also involve other regions of RNA and additional factors.

AB - In vitro termination of transcription at the attenuator site of the E. coli tryptophan (trp) operon occurs efficiently in the absence of additional factors. In contrast, an altered attenuator site created by the deletion trpΔLC1419 (which removes four of the eight consecutive TA base pairs at the termination site, but still functions partially in vivo) does not cause termination in vitro under standard conditions, even with the addition of rho factor. By varying components and conditions to the transcription reactions, we have found conditions under which termination does occur at the altered site (trp a1419), as well as conditions affecting termination on the wild-type template. RNA polymerase can terminate at trp a1419 when the analog iodo-CTP (which forms stronger base pairs with G) replaces CTP. A mutant polymerase (rpo203) that restores termination in strains carrying rho mutations can also terminate at trp a1419 at a position just past the deletion junction, suggesting that the point of termination may be specified by the remaining upstream leader sequence. Analogs such as Br-UTP and allylamine-UTP, which form stronger base pairs with A, elevate readthrough levels at the wild-type attenuator site. At low temperatures, readthrough on the wild-type template by wild-type RNA polymerase is enhanced, whereas the rpo203 enzyme still terminates efficiently. The results of these experiments suggest a model for termination of transcription in the absence of rho factor involving both RNA-RNA and RNA-DNA interactions. We propose that the response of RNA polymerase at a terminator site is governed by a balance between the formation or stability of a hairpin structure in the transcript and the strength of polymerase-stabilized base pairing between the distal nucleotides of the transcript and the DNA template. In more complex cases in vitro, or within the cell, formation or stabilization of these structures may also involve other regions of RNA and additional factors.

UR - http://www.scopus.com/inward/record.url?scp=0018868661&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0018868661&partnerID=8YFLogxK

M3 - Chapter

VL - 20

SP - 739

EP - 748

BT - Cell

ER -