scholarly journals The substrate specificity of purine phosphoribosyltransferases in Schizosaccharomyces pombe

1971 ◽  
Vol 122 (4) ◽  
pp. 415-420 ◽  
Author(s):  
A. De Groodt ◽  
E. P. Whitehead ◽  
H. Heslot ◽  
L. Poirier
Keyword(s):  
Substrate Specificity ◽  
Schizosaccharomyces Pombe ◽  
Resistant Mutant ◽  
The Other ◽  
Heat Inactivation ◽  
Hypoxanthine Phosphoribosyltransferase ◽  
Single Mutation ◽  
Adenine Phosphoribosyltransferase ◽  
Purine Analogue ◽  
Resistant Mutants

1. The activities of the purine phosphoribosyltransferases (EC 2.4.2.7 and 2.4.2.8) in purine-analogue-resistant mutants of Schizosaccharomyces pombe were checked. An 8-azathioxanthine-resistant mutant lacked hypoxanthine phosphoribosyltransferase, xanthine phosphoribosyltransferase and guanine phosphoribosyltransferase activities (EC 2.4.2.8) and appeared to carry a single mutation. Two 2,6-diaminopurine-resistant mutants retained these activities but lacked adenine phosphoribosyltransferase activity (EC 2.4.2.7). This evidence, together with data on purification and heat-inactivation patterns of phosphoribosyltransferase activities towards the various purines, strongly suggests that there are two phosphoribosyltransferase enzymes for purine bases in Schiz. pombe, one active with adenine, the other with hypoxanthine, xanthine and guanine. 2. Neither growth-medium supplements of purines nor mutations on genes involved in the pathway for new biosynthesis of purine have any influence on the amount of hypoxanthine–xanthine–guanine phosphoribosyltransferase produced by this organism.

scholarly journals Thermophilic phosphoribosyltransferases Thermus thermophilus HB27 in nucleotide synthesis

2018 ◽  
Vol 14 ◽  
pp. 3098-3105
Author(s):  
Ilja V Fateev ◽  
Ekaterina V Sinitsina ◽  
Aiguzel U Bikanasova ◽  
Maria A Kostromina ◽  
Elena S Tuzova ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Kinetic Parameters ◽  
Thermus Thermophilus ◽  
Hypoxanthine Phosphoribosyltransferase ◽  
Adenine Phosphoribosyltransferase ◽  
Nucleotide Synthesis ◽  
Nucleotide Analogues ◽  
Enzymatic Cascades ◽  
Activity Dependence ◽  
Heterocyclic Bases

Phosphoribosyltransferases are the tools that allow the synthesis of nucleotide analogues using multi-enzymatic cascades. The recombinant adenine phosphoribosyltransferase (TthAPRT) and hypoxanthine phosphoribosyltransferase (TthHPRT) from Thermus thermophilus HB27 were expressed in E.coli strains and purified by chromatographic methods with yields of 10–13 mg per liter of culture. The activity dependence of TthAPRT and TthHPRT on different factors was investigated along with the substrate specificity towards different heterocyclic bases. The kinetic parameters for TthHPRT with natural substrates were determined. Two nucleotides were synthesized: 9-(β-D-ribofuranosyl)-2-chloroadenine 5'-monophosphate (2-Сl-AMP) using TthAPRT and 1-(β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine-4-one 5'-monophosphate (Allop-MP) using TthНPRT.

scholarly journals Upstream – News in Genomics

2002 ◽  
Vol 3 (3) ◽  
pp. 221-225
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ovarian Cancer ◽  
Oryza Sativa ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Proteomic Analysis ◽  
Large Scale ◽  
Protein Complexes ◽  
The Other ◽  
Blood Samples

In recent months a bumper crop of genomes has been completed, including the fission yeast (Schizosaccharomyces pombe) and rice (Oryza sativa). Two large-scale studies ofSaccharomyces cerevisiaeprotein complexes provided a picture of the eukaryotic proteome as a network of complexes. Amongst the other stories of interest was a demonstration that proteomic analysis of blood samples can be used to detect ovarian cancer, perhaps even as early as stage I.

scholarly journals Identification of a peroxidase inhibitor that enhances kanamycin activity

2020 ◽  
Author(s):  
Zhen Hui ◽  
Shiyi Liu ◽  
Ruiqin Cui ◽  
Biao Zhou ◽  
Chunxia Hu ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Target Identification ◽  
Resistant Mutant ◽  
Kanamycin Resistance ◽  
Mutant Selection ◽  
Carbapenem Resistant ◽  
Resistant Mutants

BackgroundThe threat of antimicrobial resistance calls for more efforts in basic science, drug discovery, and clinical development, particularly gram-negative carbapenem-resistant pathogens.Objectives and methodsWhole-cell–based screening was performed to identify novel antibacterial agents against Acinetobacter baumannii ATCC19606. Spontaneously resistant mutant selection, whole-genome sequencing, and surface plasmon resonance were used for target identification and confirmation. Checkerboard titration assay was used for drug combination analysis.ResultsA small molecule named 6D1 with the chemical structure of 6-fluorobenzo[d]isothiazol-3(2H)-one was identified and exhibited activity against A. baumannii ATCC19606 strain (minimal inhibitory concentration, MIC = 1 mg/L). The mutation in the plasmid-derived ohrB gene that encodes a peroxidase was identified in spontaneously resistant mutants. Treatment of the bacteria with 6D1 resulted in increased sensitivity to peroxide such as tert-butyl hydroperoxide. The binding of 6D1 and OhrB was confirmed by surface plasmon resonance. Interestingly, the MIC of kanamycin against spontaneously resistant mutants decreased. Finally, we identified the effect of 6D1 on enhancing the antibacterial activity of kanamycin, including New Delhi metallo-β-lactamase (NDM-1)-producing carbapenem-resistant Klebsiella pneumoniae, but not in strains carrying kanamycin resistance genes.ConclusionsIn this study, we identified a peroxidase inhibitor that suppresses the growth of A. baumannii and enhances the antibacterial activity of kanamycin. We propose that peroxidase may be potentially used as a target for kanamycin adjuvant development.

Abscisic acid resistant mutants in the fern Ceratopteris: characterization and genetic analysis

1985 ◽  
Vol 63 (9) ◽  
pp. 1582-1585 ◽  
Author(s):  
Leslie G. Hickok
Keyword(s):  
Abscisic Acid ◽  
Genetic Analysis ◽  
Sexual Differentiation ◽  
Double Mutant ◽  
Acid Resistance ◽  
The Other ◽  
Additive Effects ◽  
Wild Type ◽  
Resistant Mutants ◽  
Moderate Resistance

Abscisic acid normally inhibits growth and male sexual differentiation (antheridia formation) in gametophytes of the fern Ceratopteris. Abscisic acid resistant mutants show increased growth and sexual differentiation in comparison with the wild type when cultured in the presence of abscisic acid. Two different mutants that confer resistance to the effects of abscisic acid have been fully characterized. One shows moderate resistance and the other strong resistance. The mutations involve separate but linked loci. Recombination between the loci yields double mutant (cis) recombinants that exhibit additive effects and show exceptional levels of abscisic acid resistance.

scholarly journals Baloxavir Marboxil Treatment of Nude Mice Infected With Influenza A Virus

2019 ◽  
Vol 221 (10) ◽  
pp. 1699-1702 ◽  
Author(s):  
Maki Kiso ◽  
Seiya Yamayoshi ◽  
Jurika Murakami ◽  
Yoshihiro Kawaoka
Keyword(s):  
Nude Mice ◽  
Influenza A ◽  
Body Weight Loss ◽  
Resistant Mutant ◽  
Prolonged Treatment ◽  
Drug Resistant ◽  
Neuraminidase Inhibitors ◽  
Drug Resistant Mutant ◽  
Suboptimal Dose ◽  
Resistant Mutants

Abstract Background Immunocompromised patients infected with influenza virus require prolonged treatment with neuraminidase inhibitors, because these patients are not able to eradicate the virus from the respiratory tract, leading to the emergence of drug-resistant mutant viruses. Methods In this study, we examined the efficacy of baloxavir marboxil in nude mice that were immunologically deficient. Results Daily treatment with a suboptimal dose of baloxavir marboxil increased the survival time of the virus-infected nude mice but did not clear the virus from their respiratory organs, resulting in gradual body weight loss after termination of treatment. Conclusions Despite the prolonged baloxavir marboxil treatment, few resistant mutants were detected.

scholarly journals Monoclonal Antibodies That Distinguish Antigenic Variants of Canine Parvovirus

2003 ◽  
Vol 10 (6) ◽  
pp. 1085-1089 ◽  
Author(s):  
Masato Nakamura ◽  
Kazuya Nakamura ◽  
Takayuki Miyazawa ◽  
Yukinobu Tohya ◽  
Masami Mochizuki ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Antigenic Site ◽  
Canine Parvovirus ◽  
The Other ◽  
Escape Mutants ◽  
Feline Parvovirus ◽  
Resistant Mutants ◽  
Selection Of

ABSTRACT Canine parvovirus (CPV) is classified as a member of the feline parvovirus (FPV) subgroup. CPV isolates are divided into three antigenic types: CPV type 2 (CPV-2), CPV-2a, and CPV-2b. Recently, new antigenic types of CPV were isolated from Vietnamese leopard cats and designated CPV-2c(a) or CPV-2c(b). CPV-2c viruses were distinguished from the other antigenic types of the FPV subgroup by the absence of reactivity with several monoclonal antibodies (MAbs). To characterize the antigenicity of CPV-2c, a panel of MAbs against CPV-2c was generated and epitopes recognized by these MAbs were examined by selection of escape mutants. Four MAbs were established and classified into three groups on the basis of their reactivities: MAbs which recognize CPV-2a, CPV-2b, and CPV-2c (MAbs 2G5 and 20G4); an MAb which reacts with only CPV-2b and CPV-2c(b) (MAb 21C3); and an MAb which recognizes all types of the FPV subgroup viruses (MAb 19D7). The reactivity of MAb 20G4 with CPV-2c was higher than its reactivities with CPV-2a and CPV-2b. These types of specificities of MAbs have not been reported previously. A mapping study by analysis of neutralization-resistant mutants showed that epitopes recognized by MAbs 21C3 and 19D7 belonged to antigenic site A. Substitution of the residues in site B and the other antigenic site influenced the epitope recognized by MAb 2G5. It was suggested that the epitope recognized by MAb 20G4 was related to antigenic site B. These MAbs are expected to be useful for the detection and classification of FPV subgroup isolates.

scholarly journals Contribution of Pretomanid to Novel Regimens Containing Bedaquiline with either Linezolid or Moxifloxacin and Pyrazinamide in Murine Models of Tuberculosis

2019 ◽  
Vol 63 (5) ◽  
Author(s):  
Jian Xu ◽  
Si-Yang Li ◽  
Deepak V. Almeida ◽  
Rokeya Tasneen ◽  
Kala Barnes-Boyle ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Mouse Models ◽  
Treatment Duration ◽  
Resistant Mutant ◽  
Murine Models ◽  
First Line ◽  
Independent Contribution ◽  
Resistant Mutants ◽  
Treatment Of Infection ◽  
Selection Of

ABSTRACT Novel regimens combining bedaquiline and pretomanid with either linezolid (BPaL regimen) or moxifloxacin and pyrazinamide (BPaMZ regimen) shorten the treatment duration needed to cure tuberculosis (TB) in BALB/c mice compared to that of the first-line regimen and have yielded promising results in initial clinical trials. However, the independent contribution of the investigational new drug pretomanid to the efficacy of BPaMZ has not been examined, and its contribution to BPaL has been examined only over the first 2 months of treatment. In the present study, the addition of pretomanid to BL increased bactericidal activity, prevented emergence of bedaquiline resistance, and shortened the duration needed to prevent relapse with drug-susceptible isolates by at least 2 months in BALB/c mice. Addition of pretomanid to bedaquiline, moxifloxacin, and pyrazinamide (BMZ) resulted in a 1-log10 greater CFU reduction after 1 month of treatment and/or reduced the number of mice relapsing in each of 2 experiments in BALB/c mice and in immunocompromised nude mice. Bedaquiline-resistant isolates were found at relapse in only one BMZ-treated nude mouse. Treatment of infection with a pyrazinamide-resistant mutant in BALB/c mice with BPaMZ prevented selection of bedaquiline-resistant mutants and reduced the proportion of mice relapsing compared to that for BMZ treatment alone. Among severely ill C3HeB/FeJ mice with caseous pneumonia and cavitation, BPaMZ increased median survival (≥60 versus 21 days) and reduced median lung CFU by 2.4 log10 at 1 month compared to the level for BMZ. In conclusion, in 3 different mouse models, pretomanid contributed significantly to the efficacy of the BPaMZ and BPaL regimens, including restricting the selection of bedaquiline-resistant mutants.

Efficacy of a ciprofloxacin/amikacin combination against planktonic and biofilm cultures of susceptible and low-level resistant Pseudomonas aeruginosa

2019 ◽  
Vol 74 (11) ◽  
pp. 3252-3259 ◽  
Author(s):  
Anaïs Soares ◽  
Kévin Alexandre ◽  
Fabien Lamoureux ◽  
Ludovic Lemée ◽  
François Caron ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Biofilm ◽  
The Other ◽  
Clinical Strain ◽  
Bacterial Reduction ◽  
Low Level ◽  
Mechanical Dispersion ◽  
Resistant Mutants ◽  
High Level

Abstract Background Eradicating bacterial biofilm without mechanical dispersion remains a challenge. Combination therapy has been suggested as a suitable strategy to eradicate biofilm. Objectives To evaluate the efficacy of a ciprofloxacin/amikacin combination in a model of in vitro Pseudomonas aeruginosa biofilm. Methods The antibacterial activity of ciprofloxacin and amikacin (alone, in combination and successively) was evaluated by planktonic and biofilm time–kill assays against five P. aeruginosa strains: PAO1, a WT clinical strain and three clinical strains overexpressing the efflux pumps MexAB-OprM (AB), MexXY-OprM (XY) and MexCD-OprJ (CD), respectively. Amikacin MIC was 16 mg/L for XY and ciprofloxacin MIC was 0.5 mg/L for CD. The other strains were fully susceptible to ciprofloxacin and amikacin. The numbers of total and resistant cells were determined. Results In planktonic cultures, regrowth of high-level resistant mutants was observed when CD was exposed to ciprofloxacin alone and XY to amikacin alone. Eradication was obtained with ciprofloxacin or amikacin in the other strains, or with the combination in XY and CD strains. In biofilm, bactericidal reduction after 8 h followed by a mean 4 log10 cfu/mL plateau in all strains and for all regimens was noticed. No regrowth of resistant mutants was observed whatever the antibiotic regimen. The bacterial reduction obtained with a second antibiotic used simultaneously or consecutively was not significant. Conclusions The ciprofloxacin/amikacin combination prevented the emergence of resistant mutants in low-level resistant strains in planktonic cultures. Biofilm persister cells were not eradicated, either with monotherapy or with the combination.

scholarly journals Genetic analysis of nystatin-resistant mutants ofSaccharomyces cerevisiae

1977 ◽  
Vol 30 (2) ◽  
pp. 163-177 ◽  
Author(s):  
V. Karunakaran ◽  
J. R. Johnston
Keyword(s):  
Genetic Analysis ◽  
Gene Interaction ◽  
Resistant Mutant ◽  
Modifier Gene ◽  
Modifying Factors ◽  
Resistant Mutants

SUMMARYPrimary genes, designated asNYSA, NYSD, NYSE, NYSF(dominant) andnysB,nysC(recessive) are responsible for resistance to nystatin ranging from 30 to 80 u/ml. A dominant modifier gene increases the resistance conferred byNYSFfrom 80 to 140 u/ml and a recessive modifier gene enhances resistance due toNYSAby 20 u/ml (from 40 to 60 u/ml). One nystatin-resistant mutant is apparently cytoplasmic and this ‘mutation’ suppresses specifically the action of modifying factors which increase the level of resistance conferred by theNYSAgene. Interaction resulting in additive levels of resistance is shown by geneNYSDin combination with each of the genesnysB,nysCandNYSE. A model of step-wise increases in resistance due to polygenic primary genes and nuclear and cytoplasmic modifying factors is proposed.

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