scholarly journals Biological, Biochemical, and Molecular Characterization of a New Clinical Trichophyton rubrum Isolate Resistant to Terbinafine

2006 ◽  
Vol 50 (6) ◽  
pp. 2234-2236 ◽  
Author(s):  
Colin S. Osborne ◽  
Ingrid Leitner ◽  
Bettina Hofbauer ◽  
Ceri A. Fielding ◽  
Bertrand Favre ◽  
...  
Keyword(s):  
Amino Acid ◽  
Missense Mutation ◽  
Molecular Characterization ◽  
Amino Acid Substitution ◽  
Trichophyton Rubrum ◽  
Mechanisms Of Action ◽  
Clinical Strain ◽  
Squalene Epoxidase

ABSTRACT We have characterized a new clinical strain of Trichophyton rubrum highly resistant to terbinafine but exhibiting normal susceptibility to drugs with other mechanisms of action. Resistance to terbinafine in this strain is caused by a missense mutation in the squalene epoxidase gene leading to the amino acid substitution F397L.

scholarly journals Molecular Characterization of rpoBMutations Conferring Cross-Resistance to Rifamycins on Methicillin-Resistant Staphylococcus aureus

1999 ◽  
Vol 43 (11) ◽  
pp. 2813-2816 ◽  
Author(s):  
Thomas A. Wichelhaus ◽  
Volker Schäfer ◽  
Volker Brade ◽  
Boris Böddinghaus
Keyword(s):  
Staphylococcus Aureus ◽  
Amino Acid ◽  
Molecular Characterization ◽  
Amino Acid Substitution ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Cross Resistance ◽  
Methicillin Resistant ◽  
Low Level ◽  
Level Resistance

ABSTRACT Mutations of the rpoB gene conferring resistance to rifampin were analyzed in 40 methicillin-resistant Staphylococcus aureus isolates obtained from six countries. Interestingly, the majority of clinical isolates showed multiple mutations withinrpoB. The amino acid substitution 481His→Asn was the most prevalent one, capable of conferring low-level resistance on its own. Cross-resistance to rifampin, rifabutin, and rifapentine was demonstrated for all mutants identified. The level of resistance to rifamycins correlated with both the mutation position and type of amino acid substitution.

scholarly journals Amino Acid Substitution in Trichophyton rubrum Squalene Epoxidase Associated with Resistance to Terbinafine

2005 ◽  
Vol 49 (7) ◽  
pp. 2840-2844 ◽  
Author(s):  
Colin S. Osborne ◽  
Ingrid Leitner ◽  
Bertrand Favre ◽  
Neil S. Ryder
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Trichophyton Rubrum ◽  
Clinical Isolates ◽  
Single Amino Acid ◽  
Squalene Epoxidase ◽  
Reading Frame ◽  
Resistant Phenotype ◽  
Resistant Strains ◽  
Type Sequence

ABSTRACT There has only been one clinically confirmed case of terbinafine resistance in dermatophytes, where six sequential Trichophyton rubrum isolates from the same patient were found to be resistant to terbinafine and cross-resistant to other squalene epoxidase (SE) inhibitors. Microsomal SE activity from these resistant isolates was insensitive to terbinafine, suggesting a target-based mechanism of resistance (B. Favre, M. Ghannoum, and N. S. Ryder, Med. Mycol. 42:525-529, 2004). In this study, we have characterized at the molecular level the cause of the resistant phenotype of these clinical isolates. Cloning and sequencing of the SE gene and cDNA from T. rubrum revealed the presence of an intron in the gene and an open reading frame encoding a protein of 489 residues, with an equivalent similarity (57%) to both yeast and mammalian SEs. The nucleotide sequences of SE from two terbinafine-susceptible strains were identical whereas those of terbinafine-resistant strains, serially isolated from the same patient, each contained the same single missense introducing the amino acid substitution L393F. Introduction of the corresponding substitution in the Candida albicans SE gene (L398F) and expression of this gene in Saccharomyces cerevisiae conferred a resistant phenotype to the transformants when compared to those expressing the wild-type sequence. Terbinafine resistance in these T. rubrum clinical isolates appears to be due to a single amino acid substitution in SE.

scholarly journals Molecular Characterization of Pax62Neu Through Pax610Neu: An Extension of the Pax6 Allelic Series and the Identification of Two Possible Hypomorph Alleles in the Mouse Mus musculus

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1689-1700
Author(s):  
Jack Favor ◽  
Heiko Peters ◽  
Thomas Hermann ◽  
Wolfgang Schmahl ◽  
Bimal Chatterjee ◽  
...  
Keyword(s):  
Amino Acid ◽  
Molecular Characterization ◽  
Amino Acid Substitution ◽  
Gene Dosage ◽  
Three Dimensional ◽  
Null Alleles ◽  
Target Sequence ◽  
Allelic Series ◽  
Phenotypic Analysis ◽  
Major Interest

Abstract Phenotype-based mutagenesis experiments will increase the mouse mutant resource, generating mutations at previously unmarked loci as well as extending the allelic series at known loci. Mapping, molecular characterization, and phenotypic analysis of nine independent Pax6 mutations of the mouse recovered in mutagenesis experiments is presented. Seven mutations result in premature termination of translation and all express phenotypes characteristic of null alleles, suggesting that Pax6 function requires all domains to be intact. Of major interest is the identification of two possible hypomorph mutations: Heterozygotes express less severe phenotypes and homozygotes develop rudimentary eyes and nasal processes and survive up to 36 hr after birth. Pax64Neu results in an amino acid substitution within the third helix of the homeodomain. Three-dimensional modeling indicates that the amino acid substitution interrupts the homeodomain recognition α-helix, which is critical for DNA binding. Whereas cooperative dimer binding of the mutant homeodomain to a paired-class DNA target sequence was eliminated, weak monomer binding was observed. Thus, a residual function of the mutated homeodomain may explain the hypomorphic nature of the Pax64Neu allele. Pax67Neu is a base pair substitution in the Kozak sequence and results in a reduced level of Pax6 translation product. The Pax64Neu and Pax67Neu alleles may be very useful for gene-dosage studies.

scholarly journals Molecular Characterization of the Gene Encoding a New AmpC β-Lactamase in a Clinical Strain of Acinetobacter Genomic Species 3

2004 ◽  
Vol 48 (4) ◽  
pp. 1374-1378 ◽  
Author(s):  
Alejandro Beceiro ◽  
Lourdes Dominguez ◽  
Anna Ribera ◽  
Jordi Vila ◽  
Francisca Molina ◽  
...  
Keyword(s):  
Nucleotide Sequence ◽  
Molecular Characterization ◽  
Biochemical Properties ◽  
Clinical Strain ◽  
The Novel ◽  
Gene Encoding ◽  
Genomic Species ◽  
First Time

ABSTRACT A presumptive chromosomal cephalosporinase (pI, 9.0) from a clinical strain of Acinetobacter genomic species 3 (AG3) is reported. The nucleotide sequence of this β-lactamase shows for the first time the gene encoding an AmpC enzyme in AG3. In addition, the biochemical properties of the novel AG3 AmpC β-lactamase are reported

scholarly journals Molecular characterization of Prunus necrotic ringspot virus isolated from rose in Brazil

2015 ◽  
Vol 45 (12) ◽  
pp. 2197-2200 ◽  
Author(s):  
Thor Vinícius Martins Fajardo ◽  
Monique Bezerra Nascimento ◽  
Marcelo Eiras ◽  
Osmar Nickel ◽  
Gilvan Pio-Ribeiro
Keyword(s):  
Amino Acid ◽  
Molecular Characterization ◽  
Molecular Analysis ◽  
Nucleotide Sequences ◽  
Amino Acid Sequences ◽  
Causal Agent ◽  
Ringspot Virus ◽  
Prunus Necrotic Ringspot Virus ◽  
First Time

ABSTRACT: There is no molecular characterization of Brazilian isolates of Prunus necrotic ringspot virus (PNRSV), except for those infecting peach. In this research, the causal agent of rose mosaic was determined and the movement (MP) and coat (CP) protein genes of a PNRSV isolate from rose were molecularly characterized for the first time in Brazil. The nucleotide and deduced amino acid sequences of MP and CP complete genes were aligned and compared with other isolates. Molecular analysis of the MP and CP nucleotide sequences of a Brazilian PNRSV isolate from rose and others from this same host showed highest identities of 96.7% and 98.6%, respectively, and Rose-Br isolate was classified in PV32 group.

Characterization of squalene epoxidase activity from the dermatophyte Trichophyton rubrum and its inhibition by terbinafine and other antimycotic agents.

1996 ◽  
Vol 40 (2) ◽  
pp. 443-447 ◽  
Author(s):  
B Favre ◽  
N S Ryder
Keyword(s):  
Biochemical Characterization ◽  
Trichophyton Rubrum ◽  
Side Chain ◽  
Ergosterol Biosynthesis ◽  
Squalene Epoxidase ◽  
High Potency ◽  
Whole Cells ◽  
Absolute Requirement ◽  
Tertiary Amino

Squalene epoxidase (SE) is the primary target of the allylamine antimycotic agents terbinafine and naftifine and also of the thiocarbamates. Although all of these drugs are employed primarily in dermatological therapy, SE from dermatophyte fungi has not been previously investigated. We report here the biochemical characterization of SE activity from Trichophyton rubrum and the effects of terbinafine and other inhibitors. Microsomal SE activity from T. rubrum was not dependent on soluble cytoplasmic factors but had an absolute requirement for NADPH or NADH and was stimulated by flavin adenine dinucleotide. Kinetic analyses revealed that under optimal conditions the Km for squalene was 13 microM and its Vmax was 0.71 nmol/h/mg of protein. Terbinafine was the most potent inhibitor tested, with a 50% inhibitory concentration (IC50) of 15.8 nM. This inhibition was noncompetitive with regard to the substrate squalene. A structure-activity relationship study with some analogs of terbinafine indicated that the tertiary amino structure of terbinafine was crucial for its high potency, as well as the tert-alkyl side chain. Naftifine had a lower potency (IC50, 114.6 nM) than terbinafine. Inhibition was also demonstrated by the thiocarbamates tolciclate (IC50, 28.0 nM) and tolnaftate (IC50, 51.5 nM). Interestingly, the morpholine amorolfine also displayed a weak but significant effect (IC50, 30 microM). T. rubrum SE was only slightly more sensitive (approximately twofold) to terbinafine inhibition than was the Candida albicans enzyme. Therefore, this difference cannot fully explain the much higher susceptibility (> or = 100-fold) of dermatophytes than of yeasts to this drug. The sensitivity to terbinafine of ergosterol biosynthesis in whole cells of T. rubrum (IC50, 1.5 nM) is 10-fold higher than that of SE activity, suggesting that the drug accumulates in the fungus.

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