Biology subjects

Macia Valero, A.

Publications and source records attributed to Macia Valero, A..

3 recordsLinked to original sources

bioRxiv2025

Unveiling the Molecular Architecture of Candida auris Ribosome

Candida auris is an emerging multidrug-resistant fungal pathogen causing life-threatening invasive candidiasis and bloodstream infections (candidemia), posing significant global health challenges. Despite its importance, the protein translation in pathogenic fungi is poorly characterized. Using cryo-electron microscopy and single-particle reconstruction, we resolved high-resolution structures of the 80S ribosome from C. auris in its vacant state and in complexes with three inhibitors: cycloheximide (CHX), blasticidin-S (BLS), and geneticin (G418). We uncovered a unique substitution of a key nucleotide in the P-site of the small ribosomal subunit (C1160 in C. auris), which may influence ribosome-tRNA interactions and translation fidelity. Comparative analysis of ribosome inhibitor interactions showed that resistance to CHX was observed in only two Candida species examined, while BLS binding displayed no significant differences between C. auris and S. cerevisiae, although C. auris was more sensitive to it. We identified that G418 exhibits promiscuous binding across multiple nonspecific sites, yet its primary interaction site at the decoding center remains highly conserved among Candida species. These findings provide a previously uncharacterized structure of the C. auris ribosome, highlighting novel features that may be leveraged for the development of targeted antifungal therapies to combat multidrug resistance. These insights not only enhance our understanding of ribosomal inhibitor interactions but also suggest potential biomarkers for predicting antifungal susceptibility in clinical applications.

molecular biology↗

bioRxiv2025

Pulcherriminic acid biosynthesis and Transport: Insights from a heterologous system in Saccharomyces cerevisiae

Pulcherriminic acid is an iron chelator produced by some Kluyveromyces and Metschnikowia yeasts. Its biosynthesis is encoded by the four-gene PUL cluster, where PUL1 and PUL2 are the biosynthetic enzymes, PUL3 mediates the uptake of iron-bound pulcherrimin, and PUL4 is a putative regulator. Pulcherriminic acid holds antifungal potential, as the growth of organisms unable to uptake pulcherrimin is inhibited by deficit of essential iron. Thus, a heterologous production system to further characterize and optimize its biosynthesis would be valuable. Using our in-house yeast collection and genomes available in databases, we cloned PUL1 and PUL2 genes from K. lactis and one of our wild Metschnikowia isolates and built an effective production system in S. cerevisiae able to inhibit pathogenic growth. In this context, the K. lactis genes yielded faster pulcherriminic acid production than those from the Metschnikowia isolate and a combinatorial approach showed PUL1 to be the production bottleneck. We further showed that Pul3 is an importer of pulcherrimin, but also mediates the export of pulcherriminic acid and that the growth of pathogens like Candidozyma auris and organisms encoding PUL3 in their genome, previously called "cheaters", is inhibited by pulcherriminic acid, highlighting its potential as an antimicrobial agent.

microbiology↗

bioRxiv2024

The antifungal capacity of an 681-membered collection of environmental yeast isolates

Fungal pathogens threaten human health and food security, with resistance reported across limited antifungal classes. Novel strategies to control these pathogens and food spoilers are urgently needed. Environmental yeasts provide a functionally diverse, yet underexploited potential for fungal control based on their natural competition via the secretion of iron siderophores, killer toxins (proteins) or other small molecules like volatile organic compounds or biosurfactants. However, there is a lack of standardized workflows to systematically access application- relevant yeast-based compounds and understand their molecular functioning. Towards this goal, we developed a workflow to identify and characterize yeast isolates that are active against relevant human and plant pathogens and spoilage yeasts, herein focusing on discovering yeasts that produce potential killer toxins. The workflow includes the classification of the secreted molecules and cross-comparison of their antifungal capacity using an independent calibrant. Our workflow delivered a collection of 681 yeasts of which 212 isolates (31%) displayed antagonism against at least one of our target strains. While 50% of the active yeasts showed iron-depended antagonism, likely due to siderophore production, more than 25% are potentially secreting a toxic protein. Those killer yeast candidates clustered within ten species, showed target profiles from narrow- to broad spectrum, and several showed a broad pH and temperature activity profile. Given the tools for yeast biotechnology and protein engineering available, our collection offers a foundation for genetic and molecular characterization of antifungal phenotypes, with potential for future exploitation. The scalable workflow can screen other yeast collections or adjust for different antifungal compounds.

microbiology↗