The incompatibility product of IncFII R plasmid NR1 controls gene expression in the plasmid replication region

1982 ◽  
Vol 152 (2) ◽  
pp. 829-839
Author(s):  
A M Easton ◽  
R H Rownd
Keyword(s):  
Gene Expression ◽  
Target Site ◽  
Plasmid Replication ◽  
Lacz Gene ◽  
Origin Of Replication ◽  
Wild Type ◽  
Base Pairs ◽  
Replication Region ◽  
Lambda Phages ◽  
Beta Galactosidase

The incompatibility properties of IncFII R plasmid NR1 were compared with those of two of its copy number mutants, pRR12 and pRR21. pRR12 produced an altered incompatibility product and also had an altered incompatibility target site. The target site appeared to be located within the incompatibility gene, which is located more than 1,200 base pairs from the plasmid origin of replication. The incompatibility properties of pRR21 were indistinguishable from those of NR1. Lambda phages have been constructed which contain the incompatibility region of NR1 or of one of its copy mutants fused to the lacZ gene. In lysogens constructed with these phages, beta-galactosidase was produced under the control of a promoter located within the plasmid incompatibility region. Lysogens containing prophages with the incompatibility regions from pRR12 and pRR21 produced higher levels of beta-galactosidase than did lysogens containing prophages with the incompatibility region from the wild-type NR1. The introduction into these inc-lac lysogens of pBR322 plasmids carrying the incompatibility regions of the wild-type or mutant plasmids resulted in decreased levels of beta-galactosidase production. For a given lysogen, the decrease was greater when the pBR322 derivative expressed a stronger incompatibility toward the plasmid from which the fragment in the prophage was derived. This suggested that the incompatibility product acts on its target to repress gene expression in the plasmid replication region.

Eight UCA codons differentially affect the expression of the lacZ gene in the divE42 mutant of Escherichia coli

2000 ◽  
Vol 46 (6) ◽  
pp. 577-583 ◽  
Author(s):  
Takashi Kubo ◽  
Toshiko Aiso ◽  
Reiko Ohki
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Temperature Sensitive ◽  
Lacz Gene ◽  
Permissive Temperature ◽  
Wild Type ◽  
Double Mutation ◽  
Mutant Genes ◽  
Beta Galactosidase ◽  
Serine Codons

In the divE mutant, which has a temperature-sensitive mutation in the tRNA1Ser gene, the synthesis of beta-galactosidase is dramatically decreased at the non-permissive temperature. In Escherichia coli, the UCA codon is only recognized by tRNA1Ser. Several genes containing UCA codons are normally expressed at 42°C in the divE mutant. Therefore, it is unlikely that the defect is due to the general translational deficiency of the mutant tRNA1Ser. In this study, we constructed mutant lacZ genes, in which one or several UCA codons at eight positions were replaced with other serine codons such as UCU or UCC, and we examined the expression of these mutant genes in the divE mutant. We found that a single UCA codon at position 6 or 462 was sufficient to cause the same level of reduced beta-galactosidase synthesis as that of the wild-type lacZ gene, and that the defect in beta-galactosidase synthesis was accompanied by a low level of lacZ mRNA. It was also found that introduction of an rne-1 pnp-7 double mutation restored the expression of mutant lacZ genes with only UCA codons at position 6 or 462. A polarity suppressor mutation in the rho gene had no effect on the defect in lacZ gene expression in the divE mutant. We propose a model to explain these results.Key words: divE gene, tRNA1Ser, lacZ gene expression, UCA codon.

Rescue of functional replication origins from embedded configurations in a plasmid carrying the adenovirus genome

1984 ◽  
Vol 4 (2) ◽  
pp. 302-309
Author(s):  
D Hanahan ◽  
Y Gluzman
Keyword(s):  
Viral Genome ◽  
Infectious Virus ◽  
Adenovirus Type ◽  
Small Fragment ◽  
Origin Of Replication ◽  
Wild Type ◽  
Base Pairs ◽  
Bacterial Plasmid ◽  
Dna Fragment ◽  
Adenovirus Type 5

A variant of the adenovirus type 5 genome which lacks EcoRI sites has been cloned in a bacterial plasmid after the addition of EcoRI oligonucleotide linkers to its ends. Closed circular forms of the recombinant viral genome were not infectious upon their introduction into permissive eucaryotic cells. The linear genome released by digestion of the 39-kilobase recombinant plasmid (pXAd) with EcoRI produced infectious virus at about 5% of the level of wild-type controls. The viruses which arose were indistinguishable from the parental strain, and the normal termini of the viral genome had been restored. Marker rescue experiments demonstrate that provision of a DNA fragment with a normal viral end improves infectivity. When a small fragment carrying a wild-type left end (the 0 to 2.6% ClaI-B fragment) was ligated to ClaI-linearized pXAd, virus was produced with efficiencies comparable to a similar reconstitution of the two ClaI fragments of the wild-type genome. These viruses stably carry the left-end fragment at both ends, leaving the normal right end embedded in 950 base pairs of DNA. The embedded right origin is inactive. The consensus of the analyses reported here is that a free end is a necessary configuration for the sequences which make up the adenovirus origin of replication.

Negative regulation of STE6 gene expression by the alpha 2 product of Saccharomyces cerevisiae

1984 ◽  
Vol 4 (11) ◽  
pp. 2420-2427
Author(s):  
K L Wilson ◽  
I Herskowitz
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Negative Regulator ◽  
Insertion Mutation ◽  
Lacz Gene ◽  
Alpha Cells ◽  
Type Locus ◽  
A Cells ◽  
Product Expression ◽  
Beta Galactosidase

The alpha 2 product of the alpha mating type locus of Saccharomyces cerevisiae is proposed to be a negative regulator of a set of dispersed genes concerned with specialized properties of a cells. This set of genes includes those, termed a-specific STE genes (STE2, STE6, and STE14), which are required for mating by a cells but not by alpha cells. We cloned the STE6 gene to determine whether its expression is limited to a cells and, if so, whether its expression is inhibited in alpha cells by the alpha 2 product. Expression of STE6 was assayed in two ways: by blot hybridization, RNA and by beta-galactosidase activity in strains carrying a STE6-lacZ hybrid gene. We found that STE6 expression was limited to a cells and was negatively regulated by the alpha 2 product. STE6 RNA was not detectable in strains containing the wild-type alpha 2 gene product. Expression of STE6 was at least 150-fold lower in alpha cells than in a cells, based on beta-galactosidase activities in a and alpha cells carrying the STE6-lacZ gene. These results confirmed that the alpha 2 product is a negative regulator of gene expression and showed that it acts at the level of RNA production. We also examined the phenotype of a mutant carrying an insertion mutation of the STE6 gene, the ste6::lacZ allele. In addition, an a-specific defect in mating, this mutant was greatly reduced (but not completely deficient) in a-factor production. Other phenotypes characteristic of a cells--Barrier activity, agglutination, and response to alpha-factor--were normal. STE6 thus appears to be necessary for biosynthesis of a-factor.

scholarly journals Structure and regulation of KGD1, the structural gene for yeast alpha-ketoglutarate dehydrogenase.

1989 ◽  
Vol 9 (6) ◽  
pp. 2695-2705 ◽  
Author(s):  
B Repetto ◽  
A Tzagoloff
Keyword(s):  
Nuclear Dna ◽  
Lacz Gene ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
Core Element ◽  
Plasmid Library ◽  
Alpha Ketoglutarate Dehydrogenase ◽  
Wild Type Yeast ◽  
Beta Galactosidase ◽  
Ketoglutarate Dehydrogenase

Nuclear respiratory-defective mutants of Saccharomyces cerevisiae have been screened for lesions in the mitochondrial alpha-ketoglutarate dehydrogenase complex. Strains assigned to complementation group G70 were ascertained to be deficient in enzyme activity due to mutations in the KGD1 gene coding for the alpha-ketoglutarate dehydrogenase component of the complex. The KGD1 gene has been cloned by transformation of a representative kgd1 mutant, C225/U1, with a recombinant plasmid library of wild-type yeast nuclear DNA. Transformants containing the gene on a multicopy plasmid had three- to four-times-higher alpha-ketoglutarate dehydrogenase activity than did wild-type S. cerevisiae. Substitution of the chromosomal copy of KGD1 with a disrupted allele (kgd1::URA3) induced a deficiency in alpha-ketoglutarate dehydrogenase. The sequence of the cloned region of DNA which complements kgd1 mutants was found to have an open reading frame of 3,042 nucleotides capable of coding for a protein of Mw 114,470. The encoded protein had 38% identical residues with the reported sequence of alpha-ketoglutarate dehydrogenase from Escherichia coli. Two lines of evidence indicated that transcription of KGD1 is catabolite repressed. Higher steady-state levels of KGD1 mRNA were detected in wild-type yeast grown on the nonrepressible sugar galactose than in yeast grown on high glucose. Regulation of KGD1 was also studied by fusing different 5'-flanking regions of KGD1 to the lacZ gene of E. coli and measuring the expression of beta-galactosidase in yeast. Transformants harboring a fusion of 693 nucleotides of the 5'-flanking sequence expressed 10 times more beta-galactosidase activity when grown under derepressed conditions. The response to the carbon source was reduced dramatically when the same lacZ fusion was present in a hap2 or hap3 mutant. The promoter element(s) responsible for the regulated expression of KGD1 has been mapped to the -354 to -143 region. This region contained several putative activation sites with sequences matching the core element proposed to be essential for binding of the HAP2 and HAP3 regulatory proteins.

scholarly journals NusG is an intrinsic transcription termination factor that stimulates motility and coordinates global gene expression with NusA

2020 ◽  
Author(s):  
Zachary F. Mandell ◽  
Reid T. Oshiro ◽  
Alexander V. Yakhnin ◽  
Mikhail Kashlev ◽  
Daniel B. Kearns ◽  
...  
Keyword(s):  
Gene Expression ◽  
Global Gene Expression ◽  
Wild Type ◽  
Base Pairs ◽  
Termination Factor ◽  
Transcription Termination Factor ◽  
Polymerase Pausing ◽  
The Individual ◽  
Intrinsic Transcription Termination

AbstractNusA and NusG are transcription elongation factors that stimulate RNA polymerase pausing in Bacillus subtilis. While NusA was known to function as an intrinsic termination factor, the role of NusG in this process had not been explored. To examine the individual and combinatorial roles that NusA and NusG play in intrinsic termination, Term-seq was conducted in wild type, NusA depletion, ΔnusG, and NusA depletion ΔnusG strains. We determined that NusG functions as an intrinsic termination factor that works alone and cooperatively with NusA to facilitate termination at 88% of the 1,400 identified intrinsic terminators. The loss of both proteins leads to global misregulation of gene expression. Our results indicate that NusG stimulates a sequence-specific pause that assists in the completion of suboptimal terminator hairpins with weak terminal A-U and G-U base pairs at the bottom of the stem. Moreover, the loss of NusG results in flagella and swimming motility defects.

scholarly journals The effects of mutations in the ant promoter of phage P22 depend on context.

Genetics ◽  
1988 ◽  
Vol 120 (2) ◽  
pp. 319-327
Author(s):  
D Graña ◽  
T Gardella ◽  
M M Susskind
Keyword(s):  
Context Effects ◽  
Promoter Sequence ◽  
Single Copy ◽  
Promoter Strength ◽  
Lacz Gene ◽  
Promoter Mutation ◽  
Base Pairs ◽  
Phage P22 ◽  
Beta Galactosidase

Abstract Recombination was used to construct 22 two- or three-way combinations of down- and up-mutations in Pant, a strong, near-consensus promoter of phage P22. The relative strengths of these promoters in vivo were assayed by fusing them to an ant/lacZ gene fusion and measuring beta-galactosidase levels produced by lysogens carrying the fusions on single-copy prophages. The results of these assays show that the magnitude of the effect of a promoter mutation can vary considerably when its context is changed by the presence of another mutation. In addition, as Pant approaches conformity with the consensus promoter sequence, the up-mutations decrease promoter strength, even though the same mutations increase promoter strength in the presence of a down-mutation. These context effects imply that individual consensus base pairs cannot be considered to contribute to promoter strength independently.

scholarly journals Bacterial beta-galactosidase as a marker of Rous sarcoma virus gene expression and replication.

1985 ◽  
Vol 5 (2) ◽  
pp. 281-290 ◽  
Author(s):  
P A Norton ◽  
J M Coffin
Keyword(s):  
Gene Expression ◽  
Rous Sarcoma Virus ◽  
Lacz Gene ◽  
Mrna Levels ◽  
Translational Initiation ◽  
Rous Sarcoma ◽  
Virus Life Cycle ◽  
Src Gene ◽  
Sarcoma Virus ◽  
Beta Galactosidase

We have developed a convenient and sensitive assay of eucaryotic gene expression which uses the Escherichia coli lacZ gene product, beta-galactosidase, as a nonselectable marker. This system has been applied to the analysis of Rous sarcoma virus replication and gene expression. Avian cells were transfected with plasmids encoding in-frame gene fusions of the N-terminal portion of the gag gene to a 'lacZ gene, which requires both transcriptional and translational initiation signals; these were supplied by the virus long terminal repeat and leader region. Readily detectable quantities of beta-galactosidase were synthesized in transfected cells; it was demonstrated that the levels of enzyme activity induced in such cultures increased linearly with the input DNA concentration and also correlated with mRNA levels. By using a Rous sarcoma virus-derived vector containing the src gene and a related virus as a helper, it was shown that lac sequences were compatible with all phases of the virus life cycle. gag-lacZ fusion proteins were immunoprecipitable from cultures which stably expressed lacZ as well as src. Virus rescued from stably transfected cultures resulted in continued lac and src expression in recipient cells. One particular construction was efficiently transmitted as virus, although it lacked sequences thought to be important for encapsidation of RNA into virions. The data presented here demonstrate the use of lacZ as a marker of retrovirus gene expression and replication.

scholarly journals Rescue of functional replication origins from embedded configurations in a plasmid carrying the adenovirus genome.

1984 ◽  
Vol 4 (2) ◽  
pp. 302-309 ◽  
Author(s):  
D Hanahan ◽  
Y Gluzman
Keyword(s):  
Viral Genome ◽  
Infectious Virus ◽  
Adenovirus Type ◽  
Small Fragment ◽  
Origin Of Replication ◽  
Wild Type ◽  
Base Pairs ◽  
Bacterial Plasmid ◽  
Dna Fragment ◽  
Adenovirus Type 5

A variant of the adenovirus type 5 genome which lacks EcoRI sites has been cloned in a bacterial plasmid after the addition of EcoRI oligonucleotide linkers to its ends. Closed circular forms of the recombinant viral genome were not infectious upon their introduction into permissive eucaryotic cells. The linear genome released by digestion of the 39-kilobase recombinant plasmid (pXAd) with EcoRI produced infectious virus at about 5% of the level of wild-type controls. The viruses which arose were indistinguishable from the parental strain, and the normal termini of the viral genome had been restored. Marker rescue experiments demonstrate that provision of a DNA fragment with a normal viral end improves infectivity. When a small fragment carrying a wild-type left end (the 0 to 2.6% ClaI-B fragment) was ligated to ClaI-linearized pXAd, virus was produced with efficiencies comparable to a similar reconstitution of the two ClaI fragments of the wild-type genome. These viruses stably carry the left-end fragment at both ends, leaving the normal right end embedded in 950 base pairs of DNA. The embedded right origin is inactive. The consensus of the analyses reported here is that a free end is a necessary configuration for the sequences which make up the adenovirus origin of replication.

scholarly journals Negative regulation of STE6 gene expression by the alpha 2 product of Saccharomyces cerevisiae.

1984 ◽  
Vol 4 (11) ◽  
pp. 2420-2427 ◽  
Author(s):  
K L Wilson ◽  
I Herskowitz
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Negative Regulator ◽  
Insertion Mutation ◽  
Lacz Gene ◽  
Alpha Cells ◽  
Type Locus ◽  
A Cells ◽  
Product Expression ◽  
Beta Galactosidase

The alpha 2 product of the alpha mating type locus of Saccharomyces cerevisiae is proposed to be a negative regulator of a set of dispersed genes concerned with specialized properties of a cells. This set of genes includes those, termed a-specific STE genes (STE2, STE6, and STE14), which are required for mating by a cells but not by alpha cells. We cloned the STE6 gene to determine whether its expression is limited to a cells and, if so, whether its expression is inhibited in alpha cells by the alpha 2 product. Expression of STE6 was assayed in two ways: by blot hybridization, RNA and by beta-galactosidase activity in strains carrying a STE6-lacZ hybrid gene. We found that STE6 expression was limited to a cells and was negatively regulated by the alpha 2 product. STE6 RNA was not detectable in strains containing the wild-type alpha 2 gene product. Expression of STE6 was at least 150-fold lower in alpha cells than in a cells, based on beta-galactosidase activities in a and alpha cells carrying the STE6-lacZ gene. These results confirmed that the alpha 2 product is a negative regulator of gene expression and showed that it acts at the level of RNA production. We also examined the phenotype of a mutant carrying an insertion mutation of the STE6 gene, the ste6::lacZ allele. In addition, an a-specific defect in mating, this mutant was greatly reduced (but not completely deficient) in a-factor production. Other phenotypes characteristic of a cells--Barrier activity, agglutination, and response to alpha-factor--were normal. STE6 thus appears to be necessary for biosynthesis of a-factor.

scholarly journals NusG is an intrinsic transcription termination factor that stimulates motility and coordinates gene expression with NusA

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Zachary F Mandell ◽  
Reid T Oshiro ◽  
Alexander V Yakhnin ◽  
Rishi Vishwakarma ◽  
Mikhail Kashlev ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Termination ◽  
Wild Type ◽  
Base Pairs ◽  
Termination Factor ◽  
Transcription Termination Factor ◽  
Polymerase Pausing ◽  
The Individual ◽  
Intrinsic Transcription Termination

NusA and NusG are transcription factors that stimulate RNA polymerase pausing in Bacillus subtilis. While NusA was known to function as an intrinsic termination factor in B. subtilis, the role of NusG in this process was unknown. To examine the individual and combinatorial roles that NusA and NusG play in intrinsic termination, Term-seq was conducted in wild type, NusA depletion, ΔnusG, and NusA depletion ΔnusG strains. We determined that NusG functions as an intrinsic termination factor that works alone and cooperatively with NusA to facilitate termination at 88% of the 1400 identified intrinsic terminators. Our results indicate that NusG stimulates a sequence-specific pause that assists in the completion of suboptimal terminator hairpins with weak terminal A-U and G-U base pairs at the bottom of the stem. Loss of NusA and NusG leads to global misregulation of gene expression and loss of NusG results in flagella and swimming motility defects.

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