Biology subjects

Yu, S.-R.

Publications and source records attributed to Yu, S.-R..

6 recordsLinked to original sources

bioRxiv2026

Systematic analysis reveals an Mln1-dependent trade-off between metabolic flexibility and thermotolerance in Cryptococcus neoformans

During infection, fungal pathogens must adapt to multiple environmental challenges, including changes in temperature, nutrient availability, and immune stress. Although transcriptional regulators are central to these adaptations, how individual regulators contribute to distinct environmental responses and how these responses are functionally interconnected remain poorly understood. Here, we investigated the functions of infection-associated transcription factors under distinct host-relevant conditions in Cryptococcus neoformans. Integrating in vivo expression profiling with infectivity data from signature-tagged mutagenesis, we prioritized 24 transcription factors, 12 of which were induced under host-mimicking conditions. Initial functional analyses revealed distinct roles for these transcription factors in adaptation to temperature, carbon, and nitrogen availability. Further characterization of Mln1, a fungal basic helix-loop-helix transcription factor, uncovered an unexpected connection between carbon source adaptation and thermotolerance. Mig1-dependent repression limited MLN1 expression in the presence of glucose, whereas Mln1 accumulated in the nucleus in the presence of trehalose or ethanol, but not glucose. Loss of MLN1 impaired carbon-starvation gene expression and growth on non-preferred carbon sources, particularly trehalose. Conversely, mln1{Delta} cells accumulated more intracellular trehalose and exhibited enhanced thermotolerance, yet showed reduced melanization, titan cell formation, virulence in Drosophila, and brain fungal burden in mice. Together, these results suggest that Mln1 contributes to metabolic flexibility and fungal virulence while differentially influencing thermotolerance. More broadly, these findings highlight a potential physiological trade-off between nutrient utilization and stress resistance, suggesting that these adaptive processes may be interconnected in fungal pathogens.

microbiology↗

bioRxiv2026

The protein phosphatase 2A catalytic subunit Pph22 partners with Tap42 and Rrd2 to control viability and virulence in Cryptococcus neoformans

Protein phosphatase 2A regulates eukaryotic signaling, but the function of its associated regulators remains poorly understood in the human fungal pathogen Cryptococcus neoformans. Here, we used affinity purification coupled with mass spectrometry and identified 81 candidate proteins associated with the catalytic subunit Pph22, including the scaffold subunit Tpd3, the regulator Tap42, and the protein phosphatase methylesterase 1. Conditional-expression and meiotic spore analyses supported an essential role for TAP42 in viability. We identified CNAG_05505 as the Rrd2 ortholog and detected an interaction between Rrd2 and Pph22 in a yeast two-hybrid assay. Deletion of RRD2 impaired thermotolerance, altered responses to multiple stresses and antifungal agents, reduced melanin and capsule production, delayed sexual development, and inhibited titan cell formation. Mutants also displayed altered cell wall staining and reduced expression of genes involved in chitin synthesis and deacetylation. RRD2 deletion increased basal Hog1 phosphorylation, whereas PPH22 overexpression reduced it. Double-mutant analysis revealed phenotype-dependent genetic interactions between RRD2 and HOG1. Although RRD2 deletion did not significantly alter overall survival in the Drosophila infection assay, it markedly attenuated virulence in mice: all mutant-infected mice survived the 70-day observation period, and fungal burdens were reduced across multiple organs at 21 days post-infection. These findings distinguish the essential contribution of Tap42 from the broad roles of Rrd2 in stress adaptation, morphogenesis, cell surface organization, and mammalian virulence, extending the functional analysis of the cryptococcal protein phosphatase 2A regulatory network.

microbiology↗

bioRxiv2026

Systematic histone mutagenesis reveals nucleosome-dependent maintenance of three-dimensional chromosome architecture and virulence in Cryptococcus neoformans

BackgroundGenomic stability is maintained through the coordinated regulation of DNA repair, dNTP pool balance, and histone dynamics--the three pillars of the DNA damage response. Because histones constitute the fundamental 3D physical scaffold of the genome, their precise regulation is essential for the spatial organization that dictates environmental fitness. In the radiotolerant pathogen Cryptococcus neoformans, the Rad53-Bdr1 pathway is a central DDR mediator; however, the mechanisms linking this checkpoint to histone dynamics remain poorly understood. Because conventional one-dimensional analyses cannot capture how spatial chromatin folding shapes transcriptional reprogramming, we integrated high-throughput chromosome conformation capture (Hi-C) with transcriptomic profiling to address this gap. ResultsWe demonstrate that HTA1 and HTB1, encoding H2A and H2B, are essential for viability, whereas H3 and H4 paralogs exhibit functional redundancy. Although most core histones are regulated by Rad53, HHT1 and variant HTZ1 are expressed independently of the Rad53. Notably, loss of the H3 paralog HHT2 induces growth defects under diverse stress conditions. Integrated RNA sequencing and Hi-C analyses reveal that HHT2 deletion drives transcriptional reprogramming of stress-responsive genes, coinciding with large-scale chromatin rearrangements such as A/B compartment switching and topologically associating domain boundary shifts. Furthermore, HHT2 loss impairs virulence factor formation and attenuates virulence. ConclusionOur findings identify core histones as essential architects of the 3D genome in C. neoformans. By establishing a causal link between chromatin structural collapse and transcriptional reprogramming, this study highlights 3D genome architecture as a decisive physical switch linking nucleosome-level dynamics to global transcriptional programs required for environmental survival.

microbiology↗

bioRxiv2026

Systematic profiling of WD40 proteins reveals Wcp1, a cyclophilin linking CO2/heat tolerance to acidic pH adaptation in Cryptococcus neoformans

WD40 domains are major protein-protein interaction (PPI) scaffolds, yet their contributions to fungal pathogenicity remain poorly defined. We systematically analysed 94 canonical WD40 proteins in Cryptococcus neoformans. Conditional knockdown and sporulation identified 36 essential WD40 proteins, while in vitro and in vivo profiling of 103 signature-tagged deletion strains spanning 52 genes uncovered 31 pathogenicity-related WD40 proteins, including epigenetic and post-transcriptional regulators. We identified Wcp1, a dual-domain protein whose WD40-repeat and cyclophilin domains are required for growth at 37{degrees}C under 5% CO2. Its WD40 scaffold and PPIase domain supported CO2/heat tolerance and virulence. Notably, Wcp1 couples these functions to acidic pH adaptation: wcp1{Delta} failed to grow under elevated temperature and CO2 at acidic pH, exhibited enhanced intracellular acidification, reduced macrophage survival and attenuated virulence in Drosophila and mice. Integrated transcriptomic and proteomic analyses place Wcp1 at the centre of intracellular pH homeostasis, coordinating proton transport, metabolic adaptation and stress-buffering networks.

microbiology↗

bioRxiv2026

Systematic Profiling of Essential Fungal Transcription Factors Uncovers Ezt1 as a Central Pathobiological and Morphogenic Regulator in Cryptococcus neoformans

Cryptococcus neoformans is a global fungal pathogen that causes fatal cryptococcosis, and the limitations of current antifungals underscore the urgent need for new therapeutics. Here we systematically investigate essential transcriptional regulators in C. neoformans as potential antifungal targets, developing experimental pipelines that assess growth requirement, essentiality and function through conditional gene expression, constitutive overexpression, and meiotic spore analysis. We identify one quasi-essential (growth-required but non-essential) transcription factor, Fhl1, and 13 essential transcriptional regulators, three of which are transcription factors (Ezt1, Ezt2 and Cbf1) highly divergent from counterparts in other eukaryotes. Notably, Ezt1 modulates the expression of more than 1,200 genes, controlling growth, antifungal drug and stress responses, sexual development and virulence. Our findings define the essential transcriptional regulator landscape of C. neoformans and provide a framework for prioritising divergent essential regulators, particularly Ezt1, for antifungal target discovery.

microbiology↗

bioRxiv2025

The protein phosphatase 2C domain contributes to the pathobiological function of adenylyl cyclase in Cryptococcus neoformans

Adenylyl cyclase produces cyclic adenosine monophosphate, a signalling molecule that controls fungal development and virulence. Fungal adenylyl cyclases are distinguished by the presence of a conserved protein phosphatase 2C domain, whose function remains unknown. Here we show that the protein phosphatase 2C domain of Cac1, the adenylyl cyclase of the human pathogen Cryptococcus neoformans, has an unusual structure but functions as a metal-dependent serine/threonine phosphatase. Deletion of this domain or the adenylyl cyclase catalytic domain demonstrated that the protein phosphatase 2C domain is required for full Cac1 activity, influencing melanin and capsule synthesis, sexual differentiation, titan cell formation, and cell wall integrity. Notably, loss of the protein phosphatase 2C domain induces type 2 helper T-cell-biased immunity and extensive pulmonary damage yet does not cause mortality in mice. Integrated transcriptomic and phosphoproteomic analyses further revealed shared and domain-specific signalling outputs. Together, these findings define a pivotal role for the adenylyl cyclase-linked protein phosphatase 2C domain in C. neoformans pathobiology.

microbiology↗