Biology subjects

Maroc, L.

Publications and source records attributed to Maroc, L..

7 recordsLinked to original sources

bioRxiv2026

Non-homologous end-joining is implicated in rapid and efficient caspofungin adaptation in Nakaseomyces glabratus

Antifungal resistance in Nakaseomyces glabratus is a major clinical challenge, yet the cellular processes that shape its evolution remain poorly understood. Here, we used experimental evolution to investigate the role of the error-prone double-strand break repair pathway, non-homologous end joining (NHEJ), in adaptation to fluconazole and caspofungin. Wild-type and NHEJ-deficient (lig4{Delta}) populations were evolved under antifungal selection for 25 days. Fluconazole resistance emerged rapidly in both genetic backgrounds and was associated with recurrent PDR1 mutations and aneuploidies. In contrast, caspofungin adaptation was delayed and less efficient in lig4{Delta} populations, with several lineages failing to survive. All wild-type caspofungin-evolved isolates carried canonical FKS2 hotspot mutations, whereas lig4{Delta} isolates predominantly acquired resistance through alternative genetic pathways. Caspofungin adaptation also frequently conferred cross-resistance to fluconazole and was accompanied by changes in the abundance of ergosterol-associated proteins. Together, these findings implicate NHEJ in promoting efficient evolution of FKS-mediated echinocandin resistance and demonstrate that DNA repair capacity can shape antifungal resistance trajectories in N. glabratus.

microbiology↗

bioRxiv2024

FungAMR: A comprehensive portrait of antimicrobial resistance mutations in fungi

Antimicrobial resistance (AMR) is a global threat. To optimize the use of our antifungal arsenal, we need rapid detection and monitoring tools that rely on high-quality AMR mutation data. Here, we performed a thorough manual curation of published AMR mutations in fungal pathogens to produce the FungAMR reference dataset. A total of 501 papers were curated, leading to 35,792 mutation entries all classified with the degree of evidence that supports their role in resistance. FungAMR covers 95 species, 246 genes and 208 drugs. We combined variant effect predictors with FungAMR resistance mutations and showed that these tools could be used to help predict the potential impact of mutations on AMR. Additionally, a comparative analysis among species revealed a high level of convergence in the molecular basis of resistance, highlighting some potentially universal resistance mutations. The analysis also showed that a significant number of resistance mutations lead to cross-resistance within antifungals of a class, as well as between classes for certain mutated genes. The acquisition of fungal resistance in the clinic and the field is an urging concern. Finally, we provide a computational tool, ChroQueTas, that leverages FungAMR to screen fungal genomes for AMR mutations. These resources are anticipated to have great utility for researchers in the fight against antifungal resistance.

microbiology↗

bioRxiv2024

A role for the putative error-prone polymerase REV1 in DNA damage and antifungal drug resistance in Candida albicans

Antimicrobial-induced DNA damage, and subsequent repair via upregulation of DNA repair factors, including error-prone translesion polymerases, can lead to the increased accumulation of mutations in the microbial genome, and ultimately increased risk of acquired mutations associated with antimicrobial resistance. While this phenotype is well described in bacterial species, it is less thoroughly investigated amongst microbial fungi. Here, we monitor DNA damage induced by antifungal agents in the fungal pathogen Candida albicans, and find that commonly used antifungal drugs are able to induce DNA damage, leading to the upregulation of transcripts encoding predicted error-prone polymerases and related factors. We focus on REV1, encoding a putative error-prone polymerase, and find that while deleting this gene in C. albicans leads to increased sensitivity to DNA damage, it also unexpectedly renders cells more likely to incur mutations and evolve resistance to antifungal agents. We further find that deletion of REV1 leads to a significant depletion in the uncharacterized protein Shm1, which itself plays a role in fungal mutagenesis. Together, this work lends new insight into previously uncharacterized factors with important roles in the DNA damage response, mutagenesis, and the evolution of antifungal drug resistance.

microbiology↗

bioRxiv2023

Most azole antifungal resistance mutations in the drug target provide cross-resistance and carry no intrinsic fitness cost

Azole antifungals are among the most frequently used drugs to treat fungal infections. Amino acid substitutions in and around the binding site of the azole target Erg11 (Cyp51) are a common resistance mechanism in pathogenic yeasts such as Candida albicans. How many and which mutations confer resistance, and at what cost, is however largely unknown. Here, we measure the impact of nearly 4,000 amino acid variants of the Erg11 ligand binding pocket on the susceptibility to six medical azoles. We find that a large fraction of amino acid substitutions lead to resistance (33%), most resistance mutations confer cross-resistance to two or more azoles (88%) and most importantly, only a handful of resistance mutations show a significant fitness cost in the absence of drug (9%). Our results reveal that resistance to azoles can arise through a large set of mutations and this will likely lead to azole pan-resistance, with very little evolutionary compromise. Such a resource will help inform treatment choices in clinical settings and guide the development of new drugs.

microbiology↗

bioRxiv2023

Functional genetic characterization of stress tolerance and biofilm formation in Nakaseomyces glabrata via a novel CRISPR activation system

The overexpression of genes frequently arises in Nakaseomyces (formerly Candida) glabrata via gain-of-function mutations, gene duplication or aneuploidies, with important consequences on pathogenesis traits and antifungal drug resistance. This highlights the need to develop specific genetic tools to mimic and study genetic amplification in this important fungal pathogen. Here, we report the development, validation, and applications of the first CRISPR activation (CRISPRa) system in N. glabrata for targeted genetic overexpression. Using this system, we demonstrate the ability of CRISPRa to drive high levels of gene expression in N. glabrata, and further assess optimal guide RNA targeting for robust overexpression. We demonstrate the applications of CRISPRa to overexpress genes involved in fungal pathogenesis and drug resistance, and detect corresponding phenotypic alterations in these key traits, including the characterization of novel phenotypes. Finally, we capture strain variation using our CRISPRa system in two commonly used N. glabrata genetic backgrounds. Together, this tool will expand our capacity for functional genetic overexpression in this pathogen, with numerous possibilities for future applications.

microbiology↗

bioRxiv2020

Loss of Polycomb Protein EZH2 causes major depletion of H3K27 and H3K9 tri-methylation and developmental defects in the fungus Podospora anserina

Selective gene silencing is key to development. The H3K27me3 enriched heterochromatin maintains transcription repression established during early development and regulates cell fate. Conversely, H3K9me3 enriched heterochromatin prevents differentiation but constitutes a permanent protection against transposable element. We exploited the fungus Podospora anserina, a valuable alternative to higher eukaryote models to question the biological relevance and interplay of these two distinct heterochromatin conformations. We found that H3K27me3 and H3K9me3 modifications are mutually exclusive within gene-rich regions but not within repeats. Lack of PaKmt6 EZH2-like enzyme resulted in loss of H3K27me3 and in significant H3K9me3 reduction, whereas lack of PaKmt1 SU(VAR)3-9-like enzyme caused loss of H3K9me3 only. We established that P. anserina developmental programs require H3K27me3 mediated silencing unlike most fungi studied to date. Our findings provide new insight into roles of these histone marks and into the relationship between chromatin modifications and development.

genetics↗

bioRxiv2020

A single Ho-induced double-strand break at the MAT locus is lethal in Candida glabrata

Mating-type switching is a complex mechanism that promotes sexual reproduction in Ascomycotina. In the model species Saccharomyces cerevisiae, mating-type switching is initiated by the Ho endonuclease that performs a site-specific double-strand break (DSB) at MAT, repaired by homologous recombination (HR) using one of the two silent mating type cassettes, HMLalpha and HMRa. The reasons why all the elements of the mating-type switching system have been conserved in some Ascomycotina, that do not show a sexual cycle nor mating-type switching, remain unknown. To gain insight on this phenomenon, we used the opportunistic pathogenic yeast Candida glabrata, phylogenetically close to S. cerevisiae, and for which no spontaneous and efficient mating-type switching has been observed. We have previously shown that expression of S. cerevisiaes HO gene triggers mating-type switching in C. glabrata, but this leads to massive cell death. In addition, we unexpectedly found, that not only MAT but also HML was cut in this species, suggesting the formation of multiple chromosomal DSBs upon HO induction. We now report that HMR is also cut by S. cerevisiaes Ho in wild-type strains of C. glabrata. To understand the link between mating-type switching and cell death in C. glabrata, we constructed strains mutated precisely at the Ho recognition sites. By mimicking S. cerevisiaes situation, in which HML and HMR are protected from the cut, we unexpectedly find that one DSB at MAT is sufficient to induce cell death. We demonstrate that mating-type switching in C. glabrata can be triggered using CRISPR-Cas9, without high lethality. We also show that switching is Rad51-dependent, as in S. cerevisiae but that donor preference is not conserved in C. glabrata. Altogether, these results suggest that a DSB at MAT can be repaired by HR in C. glabrata, but that it is prevented by S. cerevisiaes Ho. Author summaryMating-type switching is one of the strategies developed by fungi to promote crossing, sexual reproduction and propagation. This mechanism enables one haploid cell to give rise to a cell of the opposite mating-type so that they can mate together. It has been extensively studied in the model yeast S. cerevisiae in which it relies on a programmed double-strand break performed by the Ho endonuclease at the MAT locus which encodes the key regulators of sexual identity. Little is known about why the mating-type switching components have been conserved in species like C.glabrata, in which neither sexual reproduction nor mating-type switching is observed. We have previously shown that mating-type switching can be triggered, in C. glabrata, by expression of the HO gene from S. cerevisiae but this leads to massive cell death. We report here evidence toward a degeneration of the mating-type switching system in C. glabrata. We demonstrate that the DSB at MAT is only lethal when the Ho endonuclease performs the break, a situation unique to C. glabrata. Finally, we show that mating-type switching in C. glabrata can be triggered by CRISPR-Cas9 and without any high lethality.

genetics↗