scholarly journals Cloning of the PYR3 gene of Ustilago maydis and its use in DNA transformation.

1988 ◽  
Vol 8 (12) ◽  
pp. 5417-5424 ◽  
Author(s):  
G R Banks ◽  
S Y Taylor
Keyword(s):  
Dna Sequences ◽  
Gene Copy Number ◽  
Mutant Gene ◽  
Ustilago Maydis ◽  
Gene Copy ◽  
Wild Type ◽  
Gene Encoding ◽  
E Coli ◽  
Multiple Transcripts ◽  
Different Types

The Ustilago maydis PYR3 gene encoding dihydroorotase activity was cloned by direct complementation of Escherichia coli pyrC mutations. PYR3 transformants of E. coli pyrC mutants expressed homologous transcripts of a variety of sizes and regained dihydroorotase activity. PYR3 also complemented Saccharomyces cerevisiae ura4 mutations, and again multiple transcripts were expressed in transformants, and enzyme activity was regained. A 1.25-kilobase poly(rA)+ PYR3 transcript was detected in U. maydis itself. Linear DNA carrying the PYR3 gene transformed a U. maydis pyr3-1 pyrimidine auxotroph to prototrophy. Hybridization analysis revealed that three different types of transformants could be generated, depending on the structure of the transforming DNA used. The first type involved exchange of chromosomal mutant gene sequences with the cloned wild-type plasmid sequences. A second type had integrated linear transforming DNA at the chromosomal PYR3 locus, probably via a single crossover event. The third type had integrated transforming DNA sequences at multiple sites in the U. maydis genome. In the last two types, tandemly reiterated copies of the transforming DNA were found to have been integrated. All three types had lost the sensitivity of the parental pyr3-1 mutant to UV irradiation. They had also regained dihydroorotase activity, although its level did not correlate with the PYR3 gene copy number.

Cloning of the PYR3 gene of Ustilago maydis and its use in DNA transformation

1988 ◽  
Vol 8 (12) ◽  
pp. 5417-5424
Author(s):  
G R Banks ◽  
S Y Taylor
Keyword(s):  
Dna Sequences ◽  
Gene Copy Number ◽  
Mutant Gene ◽  
Ustilago Maydis ◽  
Gene Copy ◽  
Wild Type ◽  
Gene Encoding ◽  
E Coli ◽  
Multiple Transcripts ◽  
Different Types

The Ustilago maydis PYR3 gene encoding dihydroorotase activity was cloned by direct complementation of Escherichia coli pyrC mutations. PYR3 transformants of E. coli pyrC mutants expressed homologous transcripts of a variety of sizes and regained dihydroorotase activity. PYR3 also complemented Saccharomyces cerevisiae ura4 mutations, and again multiple transcripts were expressed in transformants, and enzyme activity was regained. A 1.25-kilobase poly(rA)+ PYR3 transcript was detected in U. maydis itself. Linear DNA carrying the PYR3 gene transformed a U. maydis pyr3-1 pyrimidine auxotroph to prototrophy. Hybridization analysis revealed that three different types of transformants could be generated, depending on the structure of the transforming DNA used. The first type involved exchange of chromosomal mutant gene sequences with the cloned wild-type plasmid sequences. A second type had integrated linear transforming DNA at the chromosomal PYR3 locus, probably via a single crossover event. The third type had integrated transforming DNA sequences at multiple sites in the U. maydis genome. In the last two types, tandemly reiterated copies of the transforming DNA were found to have been integrated. All three types had lost the sensitivity of the parental pyr3-1 mutant to UV irradiation. They had also regained dihydroorotase activity, although its level did not correlate with the PYR3 gene copy number.

Developing a Genetic System in Deinococcus radiodurans for Analyzing Mutations

Genetics ◽  
2004 ◽  
Vol 166 (2) ◽  
pp. 661-668
Author(s):  
Mandy Kim ◽  
Erika Wolff ◽  
Tiffany Huang ◽  
Lilit Garibyan ◽  
Ashlee M Earl ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Deinococcus Radiodurans ◽  
Genetic System ◽  
Base Change ◽  
Base Substitution ◽  
Wild Type ◽  
Base Pairs ◽  
E Coli ◽  
Radiation Induced ◽  
Induced Mutagenesis

Abstract We have applied a genetic system for analyzing mutations in Escherichia coli to Deinococcus radiodurans, an extremeophile with an astonishingly high resistance to UV- and ionizing-radiation-induced mutagenesis. Taking advantage of the conservation of the β-subunit of RNA polymerase among most prokaryotes, we derived again in D. radiodurans the rpoB/Rif r system that we developed in E. coli to monitor base substitutions, defining 33 base change substitutions at 22 different base pairs. We sequenced >250 mutations leading to Rif r in D. radiodurans derived spontaneously in wild-type and uvrD (mismatch-repair-deficient) backgrounds and after treatment with N-methyl-N′-nitro-N-nitrosoguanidine (NTG) and 5-azacytidine (5AZ). The specificities of NTG and 5AZ in D. radiodurans are the same as those found for E. coli and other organisms. There are prominent base substitution hotspots in rpoB in both D. radiodurans and E. coli. In several cases these are at different points in each organism, even though the DNA sequences surrounding the hotspots and their corresponding sites are very similar in both D. radiodurans and E. coli. In one case the hotspots occur at the same site in both organisms.

Differential elimination of rDNA genes in bobbed mutants of Drosophila melanogaster

1986 ◽  
Vol 6 (4) ◽  
pp. 1023-1031
Author(s):  
R Terracol ◽  
N Prud'homme
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Copy Number ◽  
Rdna Locus ◽  
Gene Copy ◽  
Specific Gene ◽  
Type I ◽  
28S Rrna ◽  
Wild Type ◽  
Y Chromosomes ◽  
Genes Encoding

In Drosophila melanogaster, the multiply repeated genes encoding 18S and 28S rRNA are located on the X and Y chromosomes. A large percentage of these repeats are interrupted in the 28S region by insertions of two types. We compared the restriction patterns from a subcloned wild-type Oregon R strain to those of spontaneous and ethyl methanesulfonate-induced bobbed mutants. Bobbed mutations were found to be deficiencies that modified the organization of the rDNA locus. Genes without insertions were deleted about twice as often as genes with type I insertions. Type II insertion genes were not decreased in number, except in the mutant having the most bobbed phenotype. Reversion to wild type was associated with an increase in gene copy number, affecting exclusively genes without insertions. One hypothesis which explains these results is the partial clustering of genes by type. The initial deletion could then be due either to an unequal crossover or to loss of material without exchange. Some of our findings indicated that deletion may be associated with an amplification phenomenon, the magnitude of which would be dependent on the amount of clustering of specific gene types at the locus.

scholarly journals Contributions of individual mechanisms to fluoroquinolone resistance in 36 Escherichia coli strains isolated from humans and animals.

1996 ◽  
Vol 40 (10) ◽  
pp. 2380-2386 ◽  
Author(s):  
M J Everett ◽  
Y F Jin ◽  
V Ricci ◽  
L J Piddock
Keyword(s):  
Escherichia Coli ◽  
Dna Sequences ◽  
Quinolone Resistance ◽  
Fluoroquinolone Resistance ◽  
Polymorphism Analysis ◽  
Single Mutation ◽  
Wild Type ◽  
Single Strand Conformational Polymorphism ◽  
E Coli ◽  
High Level

Twenty-eight human isolates of Escherichia coli from Argentina and Spain and eight veterinary isolates received from the Ministry of Agriculture Fisheries and Foods in the United Kingdom required 2 to > 128 micrograms of ciprofloxacin per ml for inhibition. Fragments of gyrA and parC encompassing the quinolone resistance-determining region were amplified by PCR, and the DNA sequences of the fragments were determined. All isolates contained a mutation in gyrA of a serine at position 83 (Ser83) to an Leu, and 26 isolates also contained a mutation of Asp87 to one of four amino acids: Asn (n = 14), Tyr (n = 6), Gly (n = 5), or His (n = 1). Twenty-four isolates contained a single mutation in parC, either a Ser80 to Ile (n = 17) or Arg (n = 2) or a Glu84 to Lys (n = 3). The role of a mutation in gyrB was investigated by introducing wild-type gyrB (pBP548) into all isolates; for three transformants MICs of ciprofloxacin were reduced; however, sequencing of PCR-derived fragments containing the gyrB quinolone resistance-determining region revealed no changes. The analogous region of parE was analyzed in 34 of 36 isolates by single-strand conformational polymorphism analysis and sequencing; however, no amino acid substitutions were discovered. The outer membrane protein and lipopolysaccharide profiles of all isolates were compared with those of reference strains, and the concentration of ciprofloxacin accumulated (with or without 100 microM carbony cyanide m-chlorophenylhydrazone [CCCP] was determined. Twenty-two isolates accumulated significantly lower concentrations of ciprofloxacin than the wild-type E. coli isolate; nine isolates accumulated less then half the concentration. The addition of CCCP increased the concentration of ciprofloxacin accumulated, and in all but one isolate the percent increase was greater than that in the control strains. The data indicate that high-level fluoroquinolone resistance in E. coli involves the acquisition of mutations at multiple loci.

scholarly journals Class I Phosphoinositide 3-Kinase PIK3CA/p110α and PIK3CB/p110β Isoforms in Endometrial Cancer

2018 ◽  
Vol 19 (12) ◽  
pp. 3931 ◽  
Author(s):  
Fatemeh Mazloumi Gavgani ◽  
Victoria Smith Arnesen ◽  
Rhîan Jacobsen ◽  
Camilla Krakstad ◽  
Erling Hoivik ◽  
...  
Keyword(s):  
Endometrial Cancer ◽  
Gene Copy Number ◽  
Biochemical Properties ◽  
Class I ◽  
Gene Copy ◽  
Gene Encoding ◽  
Cellular Processes ◽  
Pi3k Signalling ◽  
Phosphoinositide 3 Kinase ◽  
Phosphatase And Tensin Homologue

The phosphoinositide 3-kinase (PI3K) signalling pathway is highly dysregulated in cancer, leading to elevated PI3K signalling and altered cellular processes that contribute to tumour development. The pathway is normally orchestrated by class I PI3K enzymes and negatively regulated by the phosphatase and tensin homologue, PTEN. Endometrial carcinomas harbour frequent alterations in components of the pathway, including changes in gene copy number and mutations, in particular in the oncogene PIK3CA, the gene encoding the PI3K catalytic subunit p110α, and the tumour suppressor PTEN. PIK3CB, encoding the other ubiquitously expressed class I isoform p110β, is less frequently altered but the few mutations identified to date are oncogenic. This isoform has received more research interest in recent years, particularly since PTEN-deficient tumours were found to be reliant on p110β activity to sustain transformation. In this review, we describe the current understanding of the common and distinct biochemical properties of the p110α and p110β isoforms, summarise their mutations and highlight how they are targeted in clinical trials in endometrial cancer.

Molecular Characterization of Genes Coding for Wild-Type and Sulfonylurea-Resistant Acetolactate Synthase in the Cyanobacterium Synechococcus PC C7942

1990 ◽  
Vol 45 (5) ◽  
pp. 538-543 ◽  
Author(s):  
D. Friedberg ◽  
J. Seijffers
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Molecular Characterization ◽  
Amino Acid Level ◽  
Acetolactate Synthase ◽  
Mutant Gene ◽  
Wild Type ◽  
E Coli

We present here the isolation and molecular characterization of acetolactate synthase (ALS) genes from the cyanobacterium Synechococcus PCC7942 which specify a sulfonylurea-sensitive enzyme and from the sulfonylurea-resistant mutant SM3/20, which specify resistance to sulfonylurea herbicides. The ALS gene was cloned and mapped by complementation of an Escherichia coli ilv auxotroph that requires branched-chain amino acids for growth and lacks ALS activity. The cyanobacterial gene is efficiently expressed in this heterologous host. The ALS gene codes for 612 amino acids and shows high sequence homology (46%) at the amino acid level with ALS III of E. coli and with the tobacco ALS. The resistant phenotype is a consequence of proline to serine substitution in residue 115 of the deduced amino acid sequence. Functional expression of the mutant gene in wild-type Synechococcus and in E. coli confirmed that this amino-acid substitution is responsible for the resistance. Yet the deduced amino-acid sequence as compared with othjer ALS proteins supports the notion that the amino-acid context of the substitution is important for the resistance.

scholarly journals Differential elimination of rDNA genes in bobbed mutants of Drosophila melanogaster.

1986 ◽  
Vol 6 (4) ◽  
pp. 1023-1031 ◽  
Author(s):  
R Terracol ◽  
N Prud'homme
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Copy Number ◽  
Rdna Locus ◽  
Gene Copy ◽  
Specific Gene ◽  
Type I ◽  
28S Rrna ◽  
Wild Type ◽  
Y Chromosomes ◽  
Genes Encoding

In Drosophila melanogaster, the multiply repeated genes encoding 18S and 28S rRNA are located on the X and Y chromosomes. A large percentage of these repeats are interrupted in the 28S region by insertions of two types. We compared the restriction patterns from a subcloned wild-type Oregon R strain to those of spontaneous and ethyl methanesulfonate-induced bobbed mutants. Bobbed mutations were found to be deficiencies that modified the organization of the rDNA locus. Genes without insertions were deleted about twice as often as genes with type I insertions. Type II insertion genes were not decreased in number, except in the mutant having the most bobbed phenotype. Reversion to wild type was associated with an increase in gene copy number, affecting exclusively genes without insertions. One hypothesis which explains these results is the partial clustering of genes by type. The initial deletion could then be due either to an unequal crossover or to loss of material without exchange. Some of our findings indicated that deletion may be associated with an amplification phenomenon, the magnitude of which would be dependent on the amount of clustering of specific gene types at the locus.

Gain of ALK gene copy number to predict lack of response to anti-EGFR treatment in advanced chemorefractory colorectal cancer (CRC) with KRAS/NRAS/BRAF/PI3KCA wild-type status.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3641-3641
Author(s):  
Filippo Pietrantonio ◽  
Anna Tessari ◽  
Rosalba Miceli ◽  
Pamela Biondani ◽  
Federica Perrone ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Copy Number ◽  
Response Rate ◽  
Gene Copy Number ◽  
Predictive Biomarkers ◽  
Gene Copy ◽  
Wild Type ◽  
Data Set ◽  
Exact Test ◽  
Need For Treatment

3641 Background: KRAS, BRAF, NRAS and exon 20 PIK3CA quadruple wild-type CRC is associated with 41.2% response rate to anti-EGFR treatments. Even in molecular characterized patients, there is still a subset of non responders. The identification of additional predictive biomarkers is an unmet clinical need for treatment personalization. Alterations of ALK oncoprotein may interfere with the biological activity of EGFR through cross-talk of downstream signalling pathways. Methods: This retrospective analysis aimed to investigate the correlation between ALK gene copy number (GCN), assessed by fluorescence in situ hybridization (FISH), and clinical outcome in KRAS/NRAS/BRAF/PI3KCA wild-type chemorefractory advanced CRC patients receiving cetuximab or panitumumab. FISH was perfomed with break-apart ALK (2p23) probes and gain of ALK GCN was defined as a mean of 3 to 5 signals in ≥10% of cells and amplification as ≥6 signals. Association of ALK status with RECIST response was performed by Fisher’s exact test. Results: Forty-one patients were identified, of whom 17 (41%) were ALK GCN positive, whereas the remaining 24 cases (59%) were ALK GCN negative. No ALK translocations were detected. Overall response rate was 19/41 (46%). We observed a partial response in 3/17 patients with ALK GCN positive versus 16/24 patients with ALK GCN negative (18% versus 67%, respectively; P=0.0036). Kaplan-meier curves for comparison of median progression-free and overall survival, as well as correlation with ALK expression by immunohistochemistry, will be presented at the Meeting exploring the whole National Cancer Institute data-set. Conclusions: In this study population with KRAS/NRAS/BRAF/PI3KCA wild-type tumors, the response rate greater than 40% is in line with literature data. ALK GCN may be a biomarker for clinical outcome prediction in advanced chemorefractory CRC patients treated with cetuximab or panitumumab.

scholarly journals Dihydropteroate Synthase of Mycobacterium leprae and Dapsone Resistance

2000 ◽  
Vol 44 (6) ◽  
pp. 1530-1537 ◽  
Author(s):  
Diana L. Williams ◽  
Laynette Spring ◽  
Eugene Harris ◽  
Paul Roche ◽  
Thomas P. Gillis
Keyword(s):  
Dna Sequences ◽  
Inhibitory Concentration ◽  
Mycobacterium Leprae ◽  
Clinical Isolates ◽  
Missense Mutations ◽  
Wild Type ◽  
Knockout Mutant ◽  
Dihydropteroate Synthase ◽  
E Coli ◽  
Bacterial Lysates

ABSTRACT Two Mycobacterium leprae genes, folP1 andfolP2, encoding putative dihydropteroate synthases (DHPS), were studied for enzymatic activity and for the presence of mutations associated with dapsone resistance. Each gene was cloned and expressed in a folP knockout mutant of Escherichia coli(C600ΔfolP::Kmr). Expression ofM. leprae folP1 in C600ΔfolP::Kmr conferred growth on a folate-deficient medium, and bacterial lysates exhibited DHPS activity. This recombinant displayed a 256-fold-greater sensitivity to dapsone (measured by the MIC) than wild-type E. coli C600, and 50-fold less dapsone was required to block (expressed as the 50% inhibitory concentration [IC50]) the DHPS activity of this recombinant. When the folP1 genes of several dapsone-resistant M. leprae clinical isolates were sequenced, two missense mutations were identified. One mutation occurred at codon 53, substituting an isoleucine for a threonine residue (T53I) in the DHPS-1, and a second mutation occurred in codon 55, substituting an arginine for a proline residue (P55R). Transformation of the C600ΔfolP::Kmr knockout with plasmids carrying either the T53I or the P55R mutant allele did not substantially alter the DHPS activity compared to levels produced by recombinants containing wild-type M. leprae folP1. However, both mutations increased dapsone resistance, with P55R having the greatest affect on dapsone resistance by increasing the MIC 64-fold and the IC50 68-fold. These results prove that thefolP1 of M. leprae encodes a functional DHPS and that mutations within this gene are associated with the development of dapsone resistance in clinical isolates of M. leprae. Transformants created with M. leprae folP2 did not confer growth on the C600ΔfolP::Kmrknockout strain, and DNA sequences of folP2 from dapsone-susceptible and -resistant M. leprae strains were identical, indicating that this gene does not encode a functional DHPS and is not involved in dapsone resistance in M. leprae.

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