The GATA-like transcription factor Gat201 determines alkaline-restricted growth in <i>Cryptococcus neoformans</i>
Bibliographic record
Abstract
ABSTRACT The fungus Cryptococcus neoformans is an opportunistic human pathogen that causes fatal meningitis through uncontrolled proliferation in host tissues. Evasion of host defenses relies on a protective polysaccharide capsule, regulated, in part, by the GATA-like transcription factor Gat201. Gat201 additionally contributes to virulence through capsule-independent mechanisms. Here, we show that Gat201 affects the proliferation of C. neoformans : in RPMI-1640 cell culture media at an alkaline pH that restricts wild-type cell growth, gat201 ∆ strains show increased budding, growth, and viability. RNA-seq analysis shows that Gat201 pathway genes, including co-factors GAT204 and LIV3, are rapidly activated within minutes of inoculating C. neoformans in RPMI media, and strains mutated for GAT204 and, to a lesser extent, LIV3 also show improved growth. The effect of Gat201 on growth is pH-dependent: gat201 ∆ cells grow better than wild-type cells at high pH but worse than wild-type cells at neutral pH, in otherwise identical media. Together, this identifies the Gat201 pathway as an alkaline-responsive regulator of proliferation: Gat201 appears to govern an environment-dependent trade-off between proliferation and production of the defensive capsule. Furthermore, evolutionary analysis shows that Gat201 is in a subfamily of GATA-like transcription factors that is conserved within diverse fungi but absent in model yeasts. Together, our findings urge improved understanding of proliferation in diverse environmental niches in order to understand the mechanistic basis of fungal pathogenesis. IMPORTANCE Infectious microorganisms must adapt to differences between external and host environments in order to colonize and cause disease. Cryptococcus neoformans is an encapsulated fungal pathogen that can infect human airways and travel to the brain to cause life-threatening meningitis. The airway is a dynamic environment characterized by nutrient limitation, high temperature (37°C), CO 2 , and transiently high pH (>8.5). In both the lung and brain, fungal proliferation through budding is a major driver of pathogenesis; however, the regulators of Cryptococcus proliferation are poorly understood and distinct from other model yeasts. In this work, we explore how Cryptococcus adapts to shifting environments and identify that the transcription factor Gat201, known to regulate capsule production, negatively regulates proliferation under alkaline conditions. Our findings highlight the need for improved understanding of proliferation/adaptation and its regulation in non-model systems.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".