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SummaryInvasive fungal infections cause 1.6 million deaths annually, primarily in immunocompromised individuals. Mortality rates are as high as 90% due to limited number of efficacious drugs and poor drug availability. The azole class antifungal, fluconazole, is widely available and has multi-species activity but only inhibits fungal cell growth instead of killing fungal cells, necessitating long treatments. To improve fluconazole treatments, we used our novel high-throughput method, the overlap2method (O2M), to identify drugs that interact with fluconazole, either increasing or decreasing efficacy. Although serendipitous identification of these interactions is rare, O2M allows us to screen molecules five times faster than testing combinations individually and greatly enriches for interactors. We identified 40 molecules that act synergistically (amplify activity) and 19 molecules that act antagonistically (decrease efficacy) when combined with fluconazole. We found that critical frontline beta-lactam antibiotics antagonize fluconazole activity. A promising fluconazole-synergizing anticholinergic drug, dicyclomine, increases fungal cell permeability and inhibits nutrient intake when combined with fluconazole.In vivo, this combination doubled the time-to-endpoint of mice with disseminatedCryptococcus neoformansinfections. Thus, our ability to rapidly identify synergistic and antagonistic drug interactions can potentially alter the patient outcomes.

In experimental science, organisms are usually studied in isolation, but in the wild they compete and cooperate in complex communities. We report a system for cross-kingdom communication by which bacteria heritably transform yeast metabolism. An ancient biological circuit blocks yeast from using other carbon sources in the presence of glucose. [GAR[superscript +]], a protein-based epigenetic element, allows yeast to circumvent this glucose repression and use multiple carbon sources in the presence of glucose. Some bacteria secrete a chemical factor that induces [GAR[superscript +]]. [GAR[superscript +]] is advantageous to bacteria because yeast cells make less ethanol, and is advantageous to yeast because their growth and long-term viability is improved in complex carbon sources. This crosskingdom communication is broadly conserved, providing a compelling argument for its adaptive value. By heritably transforming growth and survival strategies in response to the selective pressures of life in a biological community, [GAR[superscript +]] presents a unique example of Lamarckian inheritance., G. Harold and Leila Y. Mathers Foundation, Howard Hughes Medical Institute

Several well-characterized fungal proteins act as prions, proteins capable of multiple conformations, each with different activities, at least one of which is self-propagating. Through such self-propagating changes in function, yeast prions act as protein-based elements of phenotypic inheritance. We report a prion that makes cells resistant to the glucose-associated repression of alternative carbon sources, [GAR[superscript +]] (for “resistant to glucose-associated repression,” with capital letters indicating dominance and brackets indicating its non-Mendelian character). [GAR[superscript +]] appears spontaneously at a high rate and is transmissible by non-Mendelian, cytoplasmic inheritance. Several lines of evidence suggest that the prion state involves a complex between a small fraction of the cellular complement of Pma1, the major plasma membrane proton pump, and Std1, a much lower-abundance protein that participates in glucose signaling. The Pma1 proteins from closely related Saccharomyces species are also associated with the appearance of [GAR[superscript +]]. This allowed us to confirm the relationship between Pma1, Std1, and [GAR[superscript +]] by establishing that these proteins can create a transmission barrier for prion propagation and induction in Saccharomyces cerevisiae. The fact that yeast cells employ a prion-based mechanism for heritably switching between distinct carbon source utilization strategies, and employ the plasma membrane proton pump to do so, expands the biological framework in which self-propagating protein-based elements of inheritance operate., United States. National Institutes of Health (grant GM25874)

Empty parvovirus B19 capsids were isolated from insect cells infected with a recombinant baculovirus expressing parvovirus B19 VP2 alone and also with a double-recombinant baculovirus expressing both VP1 and VP2. That VP2 alone can assemble to form capsids is a phenomenon not previously observed in parvoviruses. The stoichiometry of the capsids containing both VP1 and VP2 was similar to that previously observed in parvovirus B19-infected cells. The capsids were similar to native capsids in size and appearance, and their antigenicity was demonstrated by immunoprecipitation and enzyme-linked immunosorbent assay with B19-specific antibodies.

SummaryThe antiphagocytic polysaccharide capsule of the human fungal pathogen Cryptococcus neoformans is a major virulence attribute. However, previous studies of the pleiotropic virulence determinant Gat201, a GATA family transcription factor, suggested that capsule-independent antiphagocytic mechanisms exist. We have determined that Gat201 controls the mRNA levels of ∼1100 genes (16% of the genome) and binds the upstream regions of ∼130 genes. Seven Gat201-bound genes encode for putative and known transcription factors—including two previously implicated in virulence—suggesting an extensive regulatory network. Systematic analysis pinpointed two critical Gat201-bound genes, GAT204 (a transcription factor) and BLP1, which account for much of the capsule-independent antiphagocytic function of Gat201. A strong correlation was observed between the quantitative effects of single and double mutants on phagocytosis in vitro and on host colonization in vivo. This genetic dissection provides evidence that capsule-independent antiphagocytic mechanisms are pivotal for successful mammalian infection by C. neoformans.