Upstream stimulators for recoding

1995 ◽  
Vol 73 (11-12) ◽  
pp. 1123-1129 ◽  
Author(s):  
B. Larsen ◽  
K. Brady ◽  
J. F. Atkins ◽  
J. Peden ◽  
S. Matsufuji ◽  
...  
Keyword(s):  
Bacteriophage T4 ◽  
Gene Encoding ◽  
Dna Topoisomerase ◽  
E Coli ◽  
Optimal Spacing ◽  
A Subunit ◽  
Shine Dalgarno Sequence ◽  
Acid Domain ◽  
Frameshift Event ◽  
Amino Acid Domain

Recent progress in elucidation of 5′ stimulatory elements for translational recoding is reviewed. A 5′ Shine–Dalgarno sequence increases both +1 and −1 frameshift efficiency in several genes; examples cited include the E. coli prfB gene encoding release factor 2 and the dnaX gene encoding the γ and τ subunits of DNA polymerase III holoenzyme. The spacing between the Shine–Dalgarno sequence and the shift site is critical in both the +1 and −1 frameshift cassettes; however, the optimal spacing is quite different in the two cases. A frameshift in a mammalian chromosomal gene, ornithine decarboxylase antizyme, has recently been reported; 5′ sequences have been shown to be vital for this frameshift event. Escherichia coli bacteriophage T4 gene 60 encodes a subunit of its type II DNA topoisomerase. The mature gene 60 mRNA contains an internal 50 nucleotide region that appears to be bypassed during translation. A 16 amino acid domain of the nascent peptide is necessary for this bypass to occur.Key words: recoding, frameshifting, peptide factor, stimulatory elements.

scholarly journals Escherichia coli mutations that prevent the action of the T4 unf/alc protein map in an RNA polymerase gene.

Genetics ◽  
1988 ◽  
Vol 118 (2) ◽  
pp. 173-180
Author(s):  
L Snyder ◽  
L Jorissen
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Bacteriophage T4 ◽  
Strong Support ◽  
Rpob Gene ◽  
Late Gene Expression ◽  
Gene Encoding ◽  
E Coli ◽  
A Subunit ◽  
Phage Production

Abstract Bacteriophage T4 has the substituted base hydroxymethylcytosine in its DNA and presumably shuts off host transcription by specifically blocking transcription of cytosine-containing DNA. When T4 incorporates cytosine into its own DNA, the shutoff mechanism is directed back at T4, blocking its late gene expression and phage production. Mutations which permit T4 multiplication with cytosine DNA should be in genes required for host shutoff. The only such mutations characterized thus far have been in the phage unf/alc gene. The product of this gene is also required for the unfolding of the host nucleoid after infection, hence its dual name unf/alc. As part of our investigation of the mechanism of action of unf/alc, we have isolated Escherichia coli mutants which propagate cytosine T4 even if the phage are genotypically alc+. These same E. coli mutants are delayed in the T4-induced unfolding of their nucleoid, lending strong support to the conclusion that blocking transcription and unfolding the host nucleoid are but different manifestations of the same activity. We have mapped two of the mutations, called paf mutations for prevent alc function. They both map at about 90 min, probably in the rpoB gene encoding a subunit of RNA polymerase. From the behavior of Paf mutants, we hypothesize that the unf/alc gene product of T4 interacts somehow with the host RNA polymerase to block transcription of cytosine DNA and unfold the host nucleoid.

Glycosylated flavones as selective inhibitors of topoisomerase IV.

1997 ◽  
Vol 41 (5) ◽  
pp. 992-998 ◽  
Author(s):  
F X Bernard ◽  
S Sablé ◽  
B Cameron ◽  
J Provost ◽  
J F Desnottes ◽  
...  
Keyword(s):  
Dna Cleavage ◽  
Topoisomerase Ii ◽  
Coli Strain ◽  
Selective Inhibitors ◽  
Topoisomerase Iv ◽  
Gene Encoding ◽  
Cottonseed Flour ◽  
Dna Topoisomerase ◽  
E Coli ◽  
Pbr322 Dna

Three flavonoids which promoted Escherichia coli topoisomerase IV-dependent DNA cleavage were isolated from cottonseed flour and identified as quercetin 3-O-beta-D-glucose-[1,6]-O-alpha-L-rhamnose (rutin), quercetin 3-O-beta-D-galactose-[1,6]-O-alpha-L-rhamnose, and quercetin 3-O-beta-D-glucose (isoquercitrin). The most active one (rutin) also inhibited topoisomerase IV-dependent decatenation activity (50% inhibitory concentration, 64 microg/ml) and induced the SOS response of a permeable E. coli strain. Derivatives of quercetin glycosylated at position C-3 were shown to induce two site-specific DNA cleavages of pBR322 DNA, which were mapped by DNA sequence analysis to the gene encoding resistance to tetracycline. Cleavage at these sites was hardly detectable in cleavage reactions with quercetin or fluoroquinolones. None of the three flavonoids isolated from cottonseeds had any stimulatory activity on E. coli DNA gyrase-dependent or calf thymus topoisomerase II-dependent DNA cleavage, and they were therefore specific to topoisomerase IV. These results show that selective inhibitors of topoisomerase IV can be derived from the flavone structure. This is the first report on a DNA topoisomerase inhibitor specific for topoisomerase IV.

scholarly journals Quinolone-resistant mutants of escherichia coli DNA topoisomerase IV parC gene.

1996 ◽  
Vol 40 (3) ◽  
pp. 710-714 ◽  
Author(s):  
Y Kumagai ◽  
J I Kato ◽  
K Hoshino ◽  
T Akasaka ◽  
K Sato ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Gyrase ◽  
Mutant Gene ◽  
Missense Mutations ◽  
Topoisomerase Iv ◽  
Dna Topoisomerase ◽  
E Coli ◽  
A Subunit ◽  
Resistant Strains ◽  
Mutant Genes

Escherichia coli quinolone-resistant strains with mutations of the parC gene, which codes for a subunit of topoisomerase IV, were isolated from a quinolone-resistant gyrA mutant of DNA gyrase. Quinolone-resistant parC mutants were also identified among the quinolone-resistant clinical strains. The parC mutants became susceptible to quinolones by introduction of a parC+ plasmid. Introduction of the multicopy plasmids carrying the quinolone-resistant parC mutant gene resulted in an increase in MICs of quinolones for the parC+ and quinolone-resistant gyrA strain. Nucleotide sequences of the quinolone-resistant parC mutant genes were determined, and missense mutations at position Gly-78, Ser-80, or Glu-84, corresponding to those in the quinolone-resistance-determining region of DNA gyrase, were identified. These results indicate that topoisomerase IV is a target of quinolones in E. coli and suggest that the susceptibility of E. coli cells to quinolones is determined by sensitivity of the targets, DNA gyrase and topoisomerase IV.

scholarly journals In Vivo Transduction with Shiga Toxin 1-Encoding Phage

1998 ◽  
Vol 66 (9) ◽  
pp. 4496-4498 ◽  
Author(s):  
David W. K. Acheson ◽  
Joachim Reidl ◽  
Xiaoping Zhang ◽  
Gerald T. Keusch ◽  
John J. Mekalanos ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gastrointestinal Tract ◽  
Shiga Toxin ◽  
Recipient Strain ◽  
Gene Encoding ◽  
E Coli ◽  
A Subunit

ABSTRACT To facilitate the study of intestinal transmission of the Shiga toxin 1 (Stx1)-converting phage H-19B, Tn10d-blamutagenesis of an Escherichia coli H-19B lysogen was undertaken. Two mutants containing insertions in the gene encoding the A subunit of Stx1 were isolated. The resultant ampicillin-resistantE. coli strains lysogenic for these phages produced infectious H-19B particles but not active toxin. These lysogens were capable of transducing an E. coli recipient strain in the murine gastrointestinal tract, thereby demonstrating that lysogens of Shiga toxin-converting phages give rise to infectious virions within the host gastrointestinal tract.

scholarly journals The First Step in Polyethylene Glycol Degradation by Sphingomonads Proceeds via a Flavoprotein Alcohol Dehydrogenase Containing Flavin Adenine Dinucleotide

2001 ◽  
Vol 183 (22) ◽  
pp. 6694-6698 ◽  
Author(s):  
Manabu Sugimoto ◽  
Miwa Tanabe ◽  
Misako Hataya ◽  
Shogo Enokibara ◽  
Johannis A. Duine ◽  
...  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Flavin Adenine Dinucleotide ◽  
Gluconobacter Oxydans ◽  
Gene Encoding ◽  
E Coli ◽  
Choline Dehydrogenase ◽  
Nitrobenzyl Alcohol ◽  
A Subunit ◽  
Broad Variety ◽  
Membrane Bound

ABSTRACT Several Sphingomonas spp. utilize polyethylene glycols (PEGs) as a sole carbon and energy source, oxidative PEG degradation being initiated by a dye-linked dehydrogenase (PEG-DH) that oxidizes the terminal alcohol groups of the polymer chain. Purification and characterization of PEG-DH from Sphingomonas terraerevealed that the enzyme is membrane bound. The gene encoding this enzyme (pegA) was cloned, sequenced, and expressed inEscherichia coli. The purified recombinant enzyme was vulnerable to aggregation and inactivation, but this could be prevented by addition of detergent. It is as a homodimeric protein with a subunit molecular mass of 58.8 kDa, each subunit containing 1 noncovalently bound flavin adenine dinucleotide but not Fe or Zn. PEG-DH recognizes a broad variety of primary aliphatic and aromatic alcohols as substrates. Comparison with known sequences revealed that PEG-DH belongs to the group of glucose-methanol-choline (GMC) flavoprotein oxidoreductases and that it is a novel type of flavoprotein alcohol dehydrogenase related (percent identical amino acids) to other, so far uncharacterized bacterial, membrane-bound, dye-linked dehydrogenases: alcohol dehydrogenase from Pseudomonas oleovorans(46%); choline dehydrogenase from E. coli (40%);l-sorbose dehydrogenase from Gluconobacter oxydans (38%); and 4-nitrobenzyl alcohol dehydrogenase from aPseudomonas species (35%).

scholarly journals C-Terminal Deletions Can Suppress Temperature-Sensitive Mutations and Change Dominance in the Phage Mu Repressor

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 661-672 ◽  
Author(s):  
Jodi L Vogel ◽  
Vincent Geuskens ◽  
Lucie Desmet ◽  
N Patrick Higgins ◽  
Ariane Toussaint
Keyword(s):  
Binding Activity ◽  
Temperature Sensitive ◽  
Dna Binding Activity ◽  
Heat Stable ◽  
C Terminus ◽  
Acid Domain ◽  
Mutant Forms ◽  
Amino Acid Domain

Abstract Mutations in an N-terminal 70-amino acid domain of bacteriophage Mu's repressor cause temperature-sensitive DNA-binding activity. Surprisingly, amber mutations can conditionally correct the heat-sensitive defect in three mutant forms of the repressor gene, cts25 (D43-G), cts62 (R47-Q and cts71 (M28-I), and in the appropriate bacterial host produce a heat-stable Sts phenotype (for survival of temperature shifts). Sts repressor mutants are heat sensitive when in supE or supF hosts and heat resistant when in Sup° hosts. Mutants with an Sts phenotype have amber mutations at one of three codons, Q179, Q187, or Q190. The Sts phenotype relates to the repressor size: in Sup° hosts sts repressors are shorter by seven, 10, or 18 amino acids compared to repressors in supE or supF hosts. The truncated form of the sts62-1 repressor, which lacks 18 residues (Q179–V196), binds Mu operator DNA more stably at 42° in vitro compared to its full-length counterpart (cts62 repressor). In addition to influencing temperature sensitivity, the C-terminus appears to control the susceptibility to in vivo Clp proteolysis by influencing the multimeric structure of repressor.

scholarly journals A genetically detoxified derivative of heat-labile Escherichia coli enterotoxin induces neutralizing antibodies against the A subunit.

1994 ◽  
Vol 180 (6) ◽  
pp. 2147-2153 ◽  
Author(s):  
M Pizza ◽  
M R Fontana ◽  
M M Giuliani ◽  
M Domenighini ◽  
C Magagnoli ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cholera Toxin ◽  
Neutralizing Antibodies ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
E Coli ◽  
Heat Labile ◽  
A Subunit ◽  
Adp Ribosyltransferase ◽  
Derivatives Of

Escherichia coli enterotoxin (LT) and the homologous cholera toxin (CT) are A-B toxins that cause travelers' diarrhea and cholera, respectively. So far, experimental live and killed vaccines against these diseases have been developed using only the nontoxic B portion of these toxins. The enzymatically active A subunit has not been used because it is responsible for the toxicity and it is reported to induce a negligible titer of toxin neutralizing antibodies. We used site-directed mutagenesis to inactivate the ADP-ribosyltransferase activity of the A subunit and obtained nontoxic derivatives of LT that elicited a good titer of neutralizing antibodies recognizing the A subunit. These LT mutants and equivalent mutants of CT may be used to improve live and killed vaccines against cholera and enterotoxinogenic E. coli.

scholarly journals Genetic evidence for two protein domains and a potential new activity in bacteriophage T4 DNA polymerase.

Genetics ◽  
1990 ◽  
Vol 124 (2) ◽  
pp. 213-220 ◽  
Author(s):  
L J Reha-Krantz
Keyword(s):  
Dna Polymerase ◽  
Bacteriophage T4 ◽  
Rnase H ◽  
Ribonuclease H ◽  
Temperature Sensitive ◽  
Polymerase Gene ◽  
Dna Polymerase I ◽  
E Coli ◽  
Intragenic Complementation ◽  
Polymerase I

Abstract Intragenic complementation was detected within the bacteriophage T4 DNA polymerase gene. Complementation was observed between specific amino (N)-terminal, temperature-sensitive (ts) mutator mutants and more carboxy (C)-terminal mutants lacking DNA polymerase polymerizing functions. Protein sequences surrounding N-terminal mutation sites are similar to sequences found in Escherichia coli ribonuclease H (RNase H) and in the 5'----3' exonuclease domain of E. coli DNA polymerase I. These observations suggest that T4 DNA polymerase, like E. coli DNA polymerase I, contains a discrete N-terminal domain.

A persistent untranslated sequence within bacteriophage T4 DNA topoisomerase gene 60

Science ◽  
1988 ◽  
Vol 239 (4843) ◽  
pp. 1005-1012 ◽  
Author(s):  
W. Huang ◽  
S. Ao ◽  
S Casjens ◽  
R Orlandi ◽  
R Zeikus ◽  
...  
Keyword(s):  
Bacteriophage T4 ◽  
Dna Topoisomerase ◽  
Untranslated Sequence
Sign in / Sign up

Export Citation Format

Share Document