Identification of the sigma E subunit of Escherichia coli RNA polymerase: a second alternate sigma factor involved in high-temperature gene expression.

An Escherichia coli strain carrying an amber mutation (UAG) in rpoC, the gene encoding the beta prime subunit of RNA polymerase, was isolated after mutagenesis with nitrosoguanidine. The mutation was moved into an unmutagenized strain carrying the supD43,74 allele, which encodes a temperature-sensitive su1 amber suppressor, and sue alleles, which enhance the efficiency of the suppressor. In this background, beta prime is not synthesized at high temperature. Suppression of the mutation by the non-temperature-sensitive amber suppressor su1+ yields a protein which is functional at all temperatures examined (30, 37, and 42 degrees C).

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Roles of the Escherichia coli heat shock sigma factor 32 in early and late gene expression of bacteriophage T4.

Journal of Bacteriology ◽

10.1128/jb.170.3.1384-1388.1988 ◽

1988 ◽

Vol 170 (3) ◽

pp. 1384-1388 ◽

Cited By ~ 4

Author(s):

M W Frazier ◽

G Mosig

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Heat Shock ◽

Sigma Factor ◽

Bacteriophage T4 ◽

Late Gene ◽

Late Gene Expression

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Substitution of a Highly Conserved Histidine in the Escherichia coli Heat Shock Transcription Factor, σ32, Affects Promoter Utilization In Vitro and Leads to Overexpression of the Biofilm-Associated Flu Protein In Vivo

Journal of Bacteriology ◽

10.1128/jb.01197-07 ◽

2007 ◽

Vol 189 (23) ◽

pp. 8430-8436 ◽

Cited By ~ 2

Author(s):

Olga V. Kourennaia ◽

Pieter L. deHaseth

Keyword(s):

Escherichia Coli ◽

Heat Shock ◽

Rna Polymerase ◽

Sigma Factor ◽

Stable Complex ◽

Tryptophan Residue ◽

Specific Sequence ◽

Bacterial Rna

ABSTRACT The heat shock sigma factor (σ32 in Escherichia coli) directs the bacterial RNA polymerase to promoters of a specific sequence to form a stable complex, competent to initiate transcription of genes whose products mitigate the effects of exposure of the cell to high temperatures. The histidine at position 107 of σ32 is at the homologous position of a tryptophan residue at position 433 of the main sigma factor of E. coli, σ70. This tryptophan is essential for the strand separation step leading to the formation of the initiation-competent RNA polymerase-promoter complex. The heat shock sigma factors of all gammaproteobacteria sequenced have a histidine at this position, while in the alpha- and deltaproteobacteria, it is a tryptophan. In vitro the alanine-for-histidine substitution at position 107 (H107A) destabilizes complexes between the GroE promoter and RNA polymerase containing σ32, implying that H107 plays a role in formation or maintenance of the strand-separated complex. In vivo, the H107A substitution in σ32 impedes recovery from heat shock (exposure to 42°C), and it also leads to overexpression at lower temperatures (30°C) of the Flu protein, which is associated with biofilm formation.

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The rpoE gene encoding the sigma E (sigma 24) heat shock sigma factor of Escherichia coli.

The EMBO Journal ◽

10.1002/j.1460-2075.1995.tb07085.x ◽

1995 ◽

Vol 14 (5) ◽

pp. 1043-1055 ◽

Cited By ~ 189

Author(s):

S. Raina ◽

D. Missiakas ◽

C. Georgopoulos

Keyword(s):

Escherichia Coli ◽

Heat Shock ◽

Sigma Factor ◽

Gene Encoding ◽

Sigma E

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Bacterial Two-Hybrid Analysis of Interactions between Region 4 of the ς70 Subunit of RNA Polymerase and the Transcriptional Regulators Rsd from Escherichia coli and AlgQ from Pseudomonas aeruginosa

Journal of Bacteriology ◽

10.1128/jb.183.21.6413-6421.2001 ◽

2001 ◽

Vol 183 (21) ◽

pp. 6413-6421 ◽

Cited By ~ 45

Author(s):

Simon L. Dove ◽

Ann Hochschild

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Amino Acid ◽

Rna Polymerase ◽

Amino Acid Substitution ◽

Transcriptional Regulators ◽

Binding Motif ◽

E Coli ◽

Two Hybrid

ABSTRACT A number of transcriptional regulators mediate their effects through direct contact with the ς70 subunit ofEscherichia coli RNA polymerase (RNAP). In particular, several regulators have been shown to contact a C-terminal portion of ς70 that harbors conserved region 4. This region of ς contains a putative helix-turn-helix DNA-binding motif that contacts the −35 element of ς70-dependent promoters directly. Here we report the use of a recently developed bacterial two-hybrid system to study the interaction between the putative anti-ς factor Rsd and the ς70 subunit of E. coli RNAP. Using this system, we found that Rsd can interact with an 86-amino-acid C-terminal fragment of ς70 and also that amino acid substitution R596H, within region 4 of ς70, weakens this interaction. We demonstrated the specificity of this effect by showing that substitution R596H does not weaken the interaction between ς and two other regulators shown previously to contact region 4 of ς70. We also demonstrated that AlgQ, a homolog of Rsd that positively regulates virulence gene expression inPseudomonas aeruginosa, can contact the C-terminal region of the ς70 subunit of RNAP from this organism. We found that amino acid substitution R600H in ς70 fromP. aeruginosa, corresponding to the R596H substitution in E. coli ς70, specifically weakens the interaction between AlgQ and ς70. Taken together, our findings suggest that Rsd and AlgQ contact similar surfaces of RNAP present in region 4 of ς70 and probably regulate gene expression through this contact.

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