scholarly journals Point mutations in the squalene epoxidase erg1 and sterol 14‐α demethylase erg11 gene of T . indotineae isolates indicate that the resistant mutant strains evolved independently

Mycoses ◽  
2021 ◽  
Author(s):  
Anke Burmester ◽  
Uta‐Christina Hipler ◽  
Peter Elsner ◽  
Cornelia Wiegand
Keyword(s):  
Point Mutations ◽  
Resistant Mutant ◽  
Squalene Epoxidase ◽  
Mutant Strains

scholarly journals CHROMOSOMAL BASIS OF THE MEROZYGOSITY IN A PARTIALLY DIPLOID MUTANT OF PNEUMOCOCCUS

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 667-678
Author(s):  
Mary Lee S Ledbetter ◽  
Rollin D Hotchkiss
Keyword(s):  
High Efficiency ◽  
Point Mutations ◽  
Resistant Mutant ◽  
Chromosomal Marker ◽  
Structural Abnormality ◽  
C Cells ◽  
Wild Type ◽  
Chromosomal Locus ◽  
Low Efficiency ◽  
Derivatives Of

ABSTRACT A sulfonamide-resistant mutant of pneumococcus, sulr-c, displays a genetic instability, regularly segregating to wild type. DNA extracts of derivatives of the strain possess transforming activities for both the mutant and wild-type alleles, establishing that the strain is a partial diploid. The linkage of sulr-c to strr-61, a stable chromosomal marker, was established, thus defining a chromosomal locus for sulr-c. DNA isolated from sulr-c cells transforms two mutant recipient strains at the same low efficiency as it does a wild-type recipient, although the mutant property of these strains makes them capable of integrating classical "low-efficiency" donor markers equally as efficiently as "high efficiency" markers. Hence sulr-c must have a different basis for its low efficiency than do classical low efficiency point mutations. We suggest that the DNA in the region of the sulr-c mutation has a structural abnormality which leads both to its frequent segregation during growth and its difficulty in efficiently mediating genetic transformation.

scholarly journals Identification of the l,d-Transpeptidases Responsible for Attachment of the Braun Lipoprotein to Escherichia coli Peptidoglycan

2007 ◽  
Vol 189 (10) ◽  
pp. 3927-3931 ◽  
Author(s):  
Sophie Magnet ◽  
Samuel Bellais ◽  
Lionel Dubost ◽  
Martine Fourgeaud ◽  
Jean-Luc Mainardi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterococcus Faecium ◽  
Resistant Mutant ◽  
Cross Linking ◽  
Mutant Strains ◽  
Acyl Acceptors

ABSTRACT The l,d-transpeptidase Ldtfm catalyzes peptidoglycan cross-linking in β-lactam-resistant mutant strains of Enterococcus faecium. Here, we show that in Escherichia coli Ldtfm homologues are responsible for the attachment of the Braun lipoprotein to murein, indicating that evolutionarily related domains have been tailored to use muropeptides or proteins as acyl acceptors in the l,d-transpeptidation reaction.

scholarly journals Adenosine kinase-deficient mutant of Neurospora crassa

1982 ◽  
Vol 152 (3) ◽  
pp. 1292-1294
Author(s):  
J M Magill ◽  
P Dalke ◽  
T S Lyda ◽  
C W Magill
Keyword(s):  
Neurospora Crassa ◽  
Resistant Mutant ◽  
Adenosine Kinase ◽  
Deficient Mutant ◽  
Wild Type ◽  
Purine Nucleotides ◽  
Mutant Strains

Tubercidin-resistant mutant strains of Neurospora crassa were isolated, and at least one appeared to be deficient in adenosine kinase. No significant differences in [8-14C]adenosine labeling of purine nucleotides or nucleosides were found between the wild type and the adenosine kinase-deficient strains.

scholarly journals Suppressor Mutations in the Study of Photosystem I Biogenesis: sll0088 Is a Previously Unidentified Gene Involved in Reaction Center Accumulation in Synechocystis sp. Strain PCC 6803

2003 ◽  
Vol 185 (13) ◽  
pp. 3878-3887 ◽  
Author(s):  
Jianping Yu ◽  
Gaozhong Shen ◽  
Tao Wang ◽  
Donald A. Bryant ◽  
John H. Golbeck ◽  
...  
Keyword(s):  
Photosystem I ◽  
Point Mutations ◽  
Kanamycin Resistance ◽  
Negative Regulator ◽  
Binding Motif ◽  
Wild Type ◽  
Photoautotrophic Growth ◽  
Suppressor Mutations ◽  
Mutant Strains ◽  
Pcc 6803

ABSTRACT In previous work, some members of our group isolated mutant strains of Synechocystis sp. strain PCC 6803 in which point mutations had been inserted into the psaC gene to alter the cysteine residues to the FA and FB iron-sulfur clusters in the PsaC subunit of photosystem I (J. P. Yu, I. R. Vassiliev, Y. S. Jung, J. H. Golbeck, and L. McIntosh, J. Biol. Chem. 272:8032-8039, 1997). These mutant strains did not grow photoautotrophically due to suppressed levels of chlorophyll a and photosystem I. In the results described here, we show that suppressor mutations produced strains that are capable of photoautotrophic growth at moderate light intensity (20 μmol m−2 s−1). Two separate suppressor strains of C14SPsaC, termed C14SPsaC-R62 and C14SPsaC-R18, were studied and found to have mutations in a previously uncharacterized open reading frame of the Synechocystis sp. strain PCC 6803 genome named sll0088. C14SPsaC-R62 was found to substitute Pro for Arg at residue 161 as the result of a G482→C change in sll0088, and C14SPsaC-R18 was found to have a three-amino-acid insertion of Gly-Tyr-Phe following Cys231 as the result of a TGGTTATTT duplication at T690 in sll0088. These suppressor strains showed near-wild-type levels of chlorophyll a and photosystem I, yet the serine oxygen ligand to FB was retained as shown by the retention of the S ≥ 3/2 spin state of the [4Fe-4S] cluster. The inactivation of sll0088 by insertion of a kanamycin resistance cartridge in the primary C14SPsaC mutant produced an engineered suppressor strain capable of photoautotrophic growth. There was no difference in psaC gene expression or in the amount of PsaC protein assembled in thylakoids between the wild type and an sll0088 deletion mutant. The sll0088 gene encodes a protein predicted to be a transcriptional regulator with sequence similarities to transcription factors in other prokaryotic and eukaryotic organisms, including Arabidopsis thaliana. The protein contains a typical helix-turn-helix DNA-binding motif and can be classified as a negative regulator by phylogenetic analysis. This suggests that the product of sll0088 has a role in regulating the biogenesis of photosystem I.

scholarly journals Intrinsic resistance to terbinafine among human and animal isolates of Trichophyton mentagrophytes related to amino acid substitution in the squalene epoxidase

Infection ◽  
2020 ◽  
Vol 48 (6) ◽  
pp. 889-897 ◽  
Author(s):  
Dominik Łagowski ◽  
Sebastian Gnat ◽  
Aneta Nowakiewicz ◽  
Marcelina Osińska ◽  
Mariusz Dyląg
Keyword(s):  
Amino Acid ◽  
Fungal Infections ◽  
Single Point ◽  
Antifungal Susceptibility ◽  
Point Mutations ◽  
Trichophyton Mentagrophytes ◽  
Single Amino Acid ◽  
Squalene Epoxidase ◽  
Intrinsic Resistance ◽  
Resistant Strains

Abstract Background Dermatomycoses are the most common fungal infections in the world affecting a significant part of the human and animal population. The majority of zoophilic infections in humans are caused by Trichophyton mentagrophytes. Currently, the first-line drug for both oral and topical therapy is terbinafine. However, an increasing number of cases that are difficult to be cured with this drug have been noted in Europe and Asia. Resistance to terbinafine and other allylamines is very rare and usually correlated with point mutations in the squalene epoxidase gene resulting in single amino acid substitutions in the enzyme, which is crucial in the ergosterol synthesis pathway. Purpose Here, we report terbinafine-resistant T. mentagrophytes isolates among which one was an etiological factor of tinea capitis in a man and three were obtained from asymptomatic foxes in Poland. Methods We used the CLSI protocol to determine antifungal susceptibility profiles of naftifine, amphotericin B, griseofulvin, ketoconazole, miconazole, itraconazole, voriconazole, and ciclopirox. Moreover, the squalene epoxidase gene of the terbinafine-resistant strains was sequenced and analysed. Results In the genomes of all four resistant strains exhibiting elevated MICs to terbinafine (16 to 32 µg/ml), single-point mutations leading to Leu393Phe substitution in the squalene epoxidase enzyme were revealed. Among the other tested substances, a MIC50 value of 1 µg/ml was shown only for griseofulvin. Conclusion Finally, our study revealed that the terbinafine resistance phenomenon might not be acquired by exposure to the drug but can be intrinsic. This is evidenced by the description of the terbinafine-resistant strains isolated from the asymptomatic animals.

scholarly journals Selection and Characterization of Phage-Resistant Mutant Strains of Listeria monocytogenes Reveal Host Genes Linked to Phage Adsorption

2015 ◽  
Vol 81 (13) ◽  
pp. 4295-4305 ◽  
Author(s):  
Thomas Denes ◽  
Henk C. den Bakker ◽  
Jeffrey I. Tokman ◽  
Claudia Guldimann ◽  
Martin Wiedmann
Keyword(s):  
Listeria Monocytogenes ◽  
Mutant Strain ◽  
Teichoic Acid ◽  
Resistant Mutant ◽  
Single Mutation ◽  
Spontaneous Mutant ◽  
Wall Teichoic Acid ◽  
Content Type ◽  
Mutant Strains ◽  
Phage Resistant Mutant

ABSTRACTListeria-infecting phages are readily isolated fromListeria-containing environments, yet little is known about the selective forces they exert on their host. Here, we identified that two virulent phages, LP-048 and LP-125, adsorb to the surface ofListeria monocytogenesstrain 10403S through different mechanisms. We isolated and sequenced, using whole-genome sequencing, 69 spontaneous mutant strains of 10403S that were resistant to either one or both phages. Mutations from 56 phage-resistant mutant strains with only a single mutation mapped to 10 genes representing five loci on the 10403S chromosome. An additional 12 mutant strains showed two mutations, and one mutant strain showed three mutations. Two of the loci, containing seven of the genes, accumulated the majority (n= 64) of the mutations. A representative mutant strain for each of the 10 genes was shown to resist phage infection through mechanisms of adsorption inhibition. Complementation of mutant strains with the associated wild-type allele was able to rescue phage susceptibility for 6 out of the 10 representative mutant strains. Wheat germ agglutinin, which specifically binds toN-acetylglucosamine, bound to 10403S and mutant strains resistant to LP-048 but did not bind to mutant strains resistant to only LP-125. We conclude that mutant strains resistant to only LP-125 lack terminalN-acetylglucosamine in their wall teichoic acid (WTA), whereas mutant strains resistant to both phages have disruptive mutations in their rhamnose biosynthesis operon but still possessN-acetylglucosamine in their WTA.

scholarly journals The Effect of Detergents on Amino Acid Liberation by the N2-fixing Cyanobacterium Anabaena variabilis and 6-Fluorotryptophan-resistant Mutant Strains

Microbiology ◽  
1988 ◽  
Vol 134 (3) ◽  
pp. 689-695
Author(s):  
G. W. NIVEN ◽  
N. W. KERBY ◽  
P. ROWELL ◽  
C. A. FOSTER ◽  
W. D. P. STEWART
Keyword(s):  
Amino Acid ◽  
Resistant Mutant ◽  
Anabaena Variabilis ◽  
Mutant Strains ◽  
Cyanobacterium Anabaena
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