Promoter recognition by Escherichia coli RNA polymerase. Effects of single base pair deletions and insertions in the spacer DNA separating the -10 and -35 regions are dependent on spacer DNA sequence

Biochemistry ◽  
1993 ◽  
Vol 32 (24) ◽  
pp. 6134-6140 ◽  
Author(s):  
Sarah E. Warne ◽  
Pieter L. deHaseth
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Dna Sequence ◽  
Base Pair ◽  
Single Base ◽  
Promoter Recognition ◽  
Single Base Pair ◽  
Spacer Dna

scholarly journals Mutations in the csgD Promoter Associated with Variations in Curli Expression in Certain Strains ofEscherichia coli O157:H7

2001 ◽  
Vol 67 (5) ◽  
pp. 2367-2370 ◽  
Author(s):  
Gaylen A. Uhlich ◽  
James E. Keen ◽  
Robert O. Elder
Keyword(s):  
Escherichia Coli ◽  
Base Pair ◽  
Congo Red ◽  
Substrate Utilization ◽  
Ofescherichia Coli ◽  
Single Base ◽  
Curli Fiber ◽  
Single Base Pair ◽  
Red Dye ◽  
Promoter Mutations

ABSTRACT Single-base-pair csgD promoter mutations in human outbreak Escherichia coli O157:H7 strains ATCC 43894 and ATCC 43895 coincided with differential Congo red dye binding from curli fiber expression. Red phenotypecsgD::lacZ promoter fusions had fourfold-greater expression than white promoter fusions. Cloning the red variant csgDEFG operon into white variants induced the red phenotype. Substrate utilization differed between red and white variants.

scholarly journals Mechanisms of activation of the cryptic cel operon of Escherichia coli K12.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 473-482 ◽  
Author(s):  
L L Parker ◽  
B G Hall
Keyword(s):  
Escherichia Coli ◽  
Base Pair ◽  
Point Mutations ◽  
Insertion Sequences ◽  
Wild Type ◽  
Single Base ◽  
Escherichia Coli K12 ◽  
In The Wild ◽  
Single Base Pair ◽  
Strain Dependent

Abstract The cel (cellobiose utilization) operon of Escherichia coli K12 is not expressed in the wild-type organism. However, mutants that can express the operon and thereby utilize the beta-glucoside sugars cellobiose, arbutin and salicin are easily isolated. Two kinds of mutations are capable of activating the operon. The first involves mutations that allow the repressor to recognize the substrates cellobiose, arbutin and salicin as inducers. We have identified the sequence changes in five different active alleles and found those differences to be single base pair changes at one of two lysine codons in the repressor gene. The second kind of mutation involves the integration of the insertion sequences IS1, IS2 or IS5 into a 108-bp region 72-180 bp upstream of the start of transcription. Integration occurs at several different sites and in different orientations. Transcription of the cel operon begins at the same base pair in all mutants examined. Of 44 independent cel+ mutants, 27 were activated by point mutations and 17 were activated by insertion sequences. The preferred mechanism of activation appears to be strain dependent, since one of the parents yielded 94% insertionally activated alleles, while another yielded 100% point mutation activated alleles.

The yeast rad18 mutator specifically increases G.C----T.A transversions without reducing correction of G-A or C-T mismatches to G.C pairs

1991 ◽  
Vol 11 (1) ◽  
pp. 218-225
Author(s):  
B A Kunz ◽  
X L Kang ◽  
L Kohalmi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Synthesis ◽  
Dna Sequence ◽  
Base Pair ◽  
Mutation Frequency ◽  
Wild Type ◽  
Sequence Context ◽  
Single Base ◽  
Mutator Effect ◽  
Single Base Pair

Inactivation of the Saccharomyces cerevisiae RAD18 gene confers a mutator phenotype. To determine the specificity of this effect, a collection of 212 spontaneous SUP4-o mutants arising in a rad18 strain was characterized by DNA sequencing. Comparison of the resulting mutational spectrum with that for an isogenic wild-type (RAD18) strain revealed that the rad18 mutator specifically enhanced the frequency of single base pair substitutions. Further analysis indicated that an increase in the frequency of G.C----T.A transversions accounted for the elevated SUP4-o mutation frequency. Thus, rad18 is the first eucaryotic mutator found to generate only a particular base pair substitution. The majority of G.C pairs that were not mutated in the rad18 background were at sites where G.C----T.A events can be detected in SUP4-o, suggesting that DNA sequence context influences the rad18 mutator effect. Transformation of heteroduplex plasmid DNAs into the two strains demonstrated that the rad18 mutator did not reduce the efficiency of correcting G-A or C-T mismatches to G.C pairs or preferentially correct the mismatches to A.T pairs. We propose that the RAD18 gene product might contribute to the fidelity of DNA replication in S. cerevisiae by involvement in a process that serves to limit the formation of G-A and C-T mismatches at template guanine and cytosine sites during DNA synthesis.

scholarly journals A single base pair dominates over the novel identity of an Escherichia coli tyrosine tRNA in Saccharomyces cerevisiae.

1991 ◽  
Vol 11 (5) ◽  
pp. 2744-2751 ◽  
Author(s):  
V Trézéguet ◽  
H Edwards ◽  
P Schimmel
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Base Pair ◽  
Major Determinant ◽  
The Novel ◽  
Single Base ◽  
E Coli ◽  
Single Base Pair

The Escherichia coli su+3 tyrosine tRNA was shown recently to be a leucine-specific tRNA in Saccharomyces cerevisiae. This finding raises the possibility that some determinants for tRNA identity in E. coli may be different in S. cerevisiae. To investigate whether the fungal system is sensitive to the major determinant for alanine acceptance in E. coli, a single G3 . U70 base pair was introduced into the acceptor helix of the su+3 tyrosine tRNA. This substitution converts the identity of the E. coli suppressor in S. cerevisiae from leucine to alanine. Thus, as in E. coli, G3 . U70 is a strong determinant for alanine acceptance that can dominate over other features in a tRNA that might be recognized by alternative charging enzymes.

scholarly journals The yeast rad18 mutator specifically increases G.C----T.A transversions without reducing correction of G-A or C-T mismatches to G.C pairs.

1991 ◽  
Vol 11 (1) ◽  
pp. 218-225 ◽  
Author(s):  
B A Kunz ◽  
X L Kang ◽  
L Kohalmi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Synthesis ◽  
Dna Sequence ◽  
Base Pair ◽  
Mutation Frequency ◽  
Wild Type ◽  
Sequence Context ◽  
Single Base ◽  
Mutator Effect ◽  
Single Base Pair

Inactivation of the Saccharomyces cerevisiae RAD18 gene confers a mutator phenotype. To determine the specificity of this effect, a collection of 212 spontaneous SUP4-o mutants arising in a rad18 strain was characterized by DNA sequencing. Comparison of the resulting mutational spectrum with that for an isogenic wild-type (RAD18) strain revealed that the rad18 mutator specifically enhanced the frequency of single base pair substitutions. Further analysis indicated that an increase in the frequency of G.C----T.A transversions accounted for the elevated SUP4-o mutation frequency. Thus, rad18 is the first eucaryotic mutator found to generate only a particular base pair substitution. The majority of G.C pairs that were not mutated in the rad18 background were at sites where G.C----T.A events can be detected in SUP4-o, suggesting that DNA sequence context influences the rad18 mutator effect. Transformation of heteroduplex plasmid DNAs into the two strains demonstrated that the rad18 mutator did not reduce the efficiency of correcting G-A or C-T mismatches to G.C pairs or preferentially correct the mismatches to A.T pairs. We propose that the RAD18 gene product might contribute to the fidelity of DNA replication in S. cerevisiae by involvement in a process that serves to limit the formation of G-A and C-T mismatches at template guanine and cytosine sites during DNA synthesis.

scholarly journals Escherichia coli O157:H7 Curli Fimbriae Promotes Biofilm Formation, Epithelial Cell Invasion, and Persistence in Cattle

2020 ◽  
Vol 8 (4) ◽  
pp. 580 ◽  
Author(s):  
Haiqing Sheng ◽  
Yansong Xue ◽  
Wei Zhao ◽  
Carolyn J. Hovde ◽  
Scott A. Minnich
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Invasion ◽  
Base Pair ◽  
Biofilm Formation ◽  
Escherichia Coli O157 ◽  
Single Base ◽  
Single Base Pair ◽  
Epithelial Cell Invasion

Escherichia coli O157:H7 (O157) is noninvasive and a weak biofilm producer; however, a subset of O157 are exceptions. O157 ATCC 43895 forms biofilms and invades epithelial cells. Tn5 mutagenesis identified a mutation responsible for both phenotypes. The insertion mapped within the curli csgB fimbriae locus. Screening of O157 strains for biofilm formation and cell invasion identified a bovine and a clinical isolate with those characteristics. A single base pair A to T transversion, intergenic to the curli divergent operons csgDEFG and csgBAC, was present only in biofilm-producing and invasive strains. Using site-directed mutagenesis, this single base change was introduced into two curli-negative/noninvasive O157 strains and modified strains to form biofilms, produce curli, and gain invasive capability. Transmission electron microscopy (EM) and immuno-EM confirmed curli fibers. EM of bovine epithelial cells (MAC-T) co-cultured with curli-expressing O157 showed intracellular bacteria. The role of curli in O157 persistence in cattle was examined by challenging cattle with curli-positive and -negative O157 and comparing carriage. The duration of bovine colonization with the O157 curli-negative mutant was shorter than its curli-positive isogenic parent. These findings definitively demonstrate that a single base pair stably confers biofilm formation, epithelial cell invasion, and persistence in cattle.

A single base pair dominates over the novel identity of an Escherichia coli tyrosine tRNA in Saccharomyces cerevisiae

1991 ◽  
Vol 11 (5) ◽  
pp. 2744-2751
Author(s):  
V Trézéguet ◽  
H Edwards ◽  
P Schimmel
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Base Pair ◽  
Major Determinant ◽  
The Novel ◽  
Single Base ◽  
E Coli ◽  
Single Base Pair

The Escherichia coli su+3 tyrosine tRNA was shown recently to be a leucine-specific tRNA in Saccharomyces cerevisiae. This finding raises the possibility that some determinants for tRNA identity in E. coli may be different in S. cerevisiae. To investigate whether the fungal system is sensitive to the major determinant for alanine acceptance in E. coli, a single G3 . U70 base pair was introduced into the acceptor helix of the su+3 tyrosine tRNA. This substitution converts the identity of the E. coli suppressor in S. cerevisiae from leucine to alanine. Thus, as in E. coli, G3 . U70 is a strong determinant for alanine acceptance that can dominate over other features in a tRNA that might be recognized by alternative charging enzymes.

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