Site-Directed Mutagenesis of the 1,3-β-Glucan Synthase Catalytic Subunit of Pneumocystis jirovecii and Susceptibility Assays Suggest Its Sensitivity to Caspofungin.

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Version: Author's accepted manuscript
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Serval ID
serval:BIB_146F1DB3AA27
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Site-Directed Mutagenesis of the 1,3-β-Glucan Synthase Catalytic Subunit of Pneumocystis jirovecii and Susceptibility Assays Suggest Its Sensitivity to Caspofungin.
Journal
Antimicrobial agents and chemotherapy
Author(s)
Luraschi A., Richard S., Hauser P.M.
ISSN
1098-6596 (Electronic)
ISSN-L
0066-4804
Publication state
Published
Issued date
12/2018
Peer-reviewed
Oui
Volume
62
Number
12
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't
Publication Status: epublish
Abstract
The echinocandin caspofungin inhibits the catalytic subunit Gsc1 of the enzymatic complex synthesizing 1,3-β-glucan, an essential compound of the fungal wall. Studies with rodents showed that caspofungin is effective against Pneumocystis asci. However, its efficacy against asci of Pneumocystis jirovecii, the species infecting exclusively humans, remains controversial. The aim of this study was to assess the sensitivity to caspofungin of the P. jirovecii Gsc1 subunit, as well as of those of Pneumocystis carinii and Pneumocystis murina infecting, respectively, rats and mice. In the absence of an established in vitro culture method for Pneumocystis species, we used functional complementation of the Saccharomyces cerevisiae gsc1 deletant. In the fungal pathogen Candida albicans, mutations leading to amino acid substitutions in Gsc1 confer resistance to caspofungin. We introduced the corresponding mutations into the Pneumocystis gsc1 genes using site-directed mutagenesis. In spot dilution tests, the sensitivity to caspofungin of the complemented strains decreased with the number of mutations introduced, suggesting that the wild-type enzymes are sensitive. The MICs of caspofungin determined by Etest and YeastOne for strains complemented with Pneumocystis enzymes (respectively, 0.125 and 0.12 μg/ml) were identical to those upon complementation with the enzyme of C. albicans, for which caspofungin presents low MICs. However, they were lower than the MICs upon complementation with the enzyme of the resistant species Candida parapsilosis (0.19 and 0.25 μg/ml). Sensitivity levels of Gsc1 enzymes of the three Pneumocystis species were similar. Our results suggest that P. jirovecii is sensitive to caspofungin during infections, as are P. carinii and P. murina.
Keywords
Antifungal Agents/pharmacology, Caspofungin/pharmacology, Fungal Proteins/genetics, Fungal Proteins/metabolism, Genetic Complementation Test, Glucosyltransferases/genetics, Glucosyltransferases/metabolism, Microbial Sensitivity Tests, Mutagenesis, Site-Directed, Pneumocystis Infections/drug therapy, Pneumocystis Infections/microbiology, Pneumocystis carinii/drug effects, Pneumocystis carinii/genetics, Protein Subunits/genetics, Saccharomyces cerevisiae/drug effects, Saccharomyces cerevisiae/genetics, Pneumocystis , drug resistance, drug sensitivity, echinocandins, heterologous functional complementation
Pubmed
Web of science
Open Access
Yes
Create date
29/10/2018 9:42
Last modification date
21/10/2019 13:19
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