SUMMARY Determining the composition of protein complexes is an essential step towards understanding the cell as an integrated system. Using co-affinity purification coupled to mass spectrometry analysis, we examined protein associations involving nearly five thousand individual, FLAG-HA epitope-tagged Drosophila proteins. Stringent analysis of these data, based on a novel statistical framework to define individual protein-protein interactions, led to the generation of a Drosophila Protein interaction Map (DPiM) encompassing 556 protein complexes. The high quality of DPiM and its usefulness as a paradigm for metazoan proteomes is apparent from the recovery of many known complexes, significant enrichment for shared functional attributes and validation in human cells. DPiM defines potential novel members for several important protein complexes and assigns functional links to 586 protein-coding genes lacking previous experimental annotation. DPiM represents, to our knowledge, the largest metazoan protein complex map and provides a valuable resource for analysis of protein complex evolution.

The authors note that in the abstract, lines 22-26, "To our knowledge, these results provide the first molecular insights into the secretome of P. destructans, and identify serine endopeptidases that have the clear potential to facilitate tissue invasion and pathogenesis in the mammalian host" were modified to correct an editorial oversight that occurred during the revision of the manuscript. The sentence has been corrected to read "These results provide molecular insights into the secretome of P. destructans, and identify serine endopeptidases that have the clear potential to facilitate tissue invasion and pathogenesis in the mammalian host." We apologize for this oversight.Also in the significance statement, lines 1-3, "To our knowledge, this work is the first to identify molecular factors produced by the fungus Pseudogymnoascus destructans, the causative agent of white-nose syndrome in bats" has similarly been corrected to read "This work identifies molecular factors produced by the fungus Pseudogymnoascus destructans, the causative agent of white-nose syndrome in bats."The online version has been corrected.www.pnas.org/cgi

Research on human fungal pathogens has historically taken a backseat to other infectious diseases, perhaps due to a common misperception that fungi largely cause superficial infections [1]. In reality, fungi can be life-threatening to those who become immunocompromised during medical procedures or through conditions such as HIV and diabetes. Invasive fungal infections are estimated to kill over 1 million people every year, with mortality rates reaching 50% [2]. Significant challenges to the treatment of fungal infections include the limited availability of antifungals and the innate ability of fungi to rapidly evolve and adapt to fluctuating conditions. This adaptive ability is partially driven by extensive genomic plasticity, with many species acquiring diverse ploidy states, chromosomal rearrangements, and point mutations during host colonization [3-8]. Genetic plasticity enables rapid increases in virulence and antifungal drug resistance, which often translate to poor disease outcomes. Short-term evolution (microevolution) strategies in fungal pathogens are therefore essential for environmental adaptation in the mammalian host, and their study can inform adaptive mechanisms in other eukaryotes. Ploidy shifts enable rapid fitness jumps under stressful conditions Many clinically relevant fungi display dynamic changes in ploidy, including both karyotypic variations (number of sets of chromosomes) as well as aneuploidy (imbalance in chromosome copy number). Some fungal pathogens exist as stable haploid, diploid, or polyploid cells, but ploidy can change upon shifting conditions. Alterations in baseline ploidy have been described for some of the most prevalent genera (Candida, Cryptococcus, and Aspergillus) and are often selected for in the host or during antifungal treatment. Extra chromosomes are common in isolates from human infections [5, 6, 8, 9] and after passage through mammalian hosts during experimental microevolution [10-12]. Under nutrient starvation, Candida albicans isolates can favor either near-haploid or near-diploid states, indicating that karyotypic reduction can provide an efficient adaptive route in some conditions [13]. Aneuploidy is also common in C. albicans and in Cryptococcus neoformans lineages and has been linked to increased virulence and drug resistance [14] [15]. Chromosomal duplication can mediate adaptation through gene dosage, as transcript levels are often proportional to gene copy number [16]. This can be seen in both C. albicans and Cryptococcus species, for which antifungal treatment selects for increased copies of chromosomes or chromosomal segments containing drug targets and/or efflux pumps. Thus, clinical isolates of Cryptococcus lineages VNI and VGI that persisted during fluconazole therapy were frequently disomic for chromosome 1 [5]. Analogous in vitro fluconazole treatment of Cryptococcus lineages VNI and VNIV selected for disomy of

Pseudogymnoascus destructans is the fungal pathogen responsible for White-nose Syndrome (WNS), a disease that has killed millions of bats in North America over the last decade. A major obstacle to research on P. destructans has been the lack of a tractable infection model for monitoring virulence. Here, we establish a high-throughput model of infection using larvae of Galleria mellonella, an invertebrate used to study host-pathogen interactions for a wide range of microbial species. We demonstrate that P. destructans can kill G. mellonella larvae in an inoculum-dependent manner when infected larvae are housed at 13°C or 18°C. Larval killing is an active process, as heat-killed P. destructans spores caused significantly decreased levels of larval death compared to live spores. We also show that fungal spores that were germinated prior to inoculation were able to kill larvae 3–4 times faster than non-germinated spores. Lastly, we identified chemical inhibitors of P. destructans and used G. mellonella to evaluate these inhibitors for their ability to reduce virulence. We demonstrate that amphotericin B can effectively block larval killing by P. destructans and thereby establish that this infection model can be used to screen biocontrol agents against this fungal pathogen.

Pseudogymnoascus destructans is a pathogenic fungus responsible for White-nose Syndrome (WNS), a disease afflicting multiple species of North American bats. Pseudogymnoascus destructans infects susceptible bats during hibernation, invading dermal tissue and causing extensive tissue damage. In contrast, other Pseudogymnoascus species are non-pathogenic and cross-species comparisons may therefore reveal factors that contribute to virulence. In this study, we compared the secretome of P. destructans with that from several closely related Pseudogymnoascus species. A diverse set of hydrolytic enzymes were identified, including a putative serine peptidase, PdCP1, that was unique to the P. destructans secretome. A recombinant form of PdCP1 was purified and substrate preference determined using a multiplexed-substrate profiling method based on enzymatic degradation of a synthetic peptide library and analysis by mass spectrometry. Most peptide substrates were sequentially truncated from the carboxyl-terminus revealing that this enzyme is a bona fide carboxypeptidase. Peptides with arginine located close to the carboxyl-terminus were rapidly cleaved, and a fluorescent substrate containing arginine was therefore used to characterize PdCP1 activity and to screen a selection of peptidase inhibitors. Antipain and leupeptin were found to be the most potent inhibitors of PdCP1 activity.

Several Candida species can undergo a heritable and reversible transition from a ‘white’ state to a mating proficient ‘opaque’ state. This ability relies on highly interconnected transcriptional networks that control cell type-specific gene expression programs over multiple generations. Candida albicans, the most prominent pathogenic Candida species, provides a well-studied paradigm for the white-opaque transition. In this species, a network of at least eight transcriptional regulators controls the balance between white and opaque states that have distinct morphologies, transcriptional profiles and physiological properties. Given the reversible nature and the high frequency of white-opaque transitions, it is widely assumed that this switch is governed by epigenetic mechanisms that occur independently of any changes in DNA sequence. However, a direct genomic comparison between white and opaque cells has yet to be performed. Here, we present a whole genome comparative analysis of C. albicans white and opaque cells. This analysis revealed rare genetic changes between cell states, none of which are linked to white-opaque switching. This result is consistent with epigenetic mechanisms controlling cell state differentiation in C. albicans and provides direct evidence against a role for genetic variation in mediating the switch.

Pseudogymnoascus destructans is the fungal pathogen responsible for White-nose Syndrome (WNS), a disease that has killed millions of bats in North America over the last decade. A major obstacle to research on P. destructans has been the lack of a tractable infection model for monitoring virulence. Here, we establish a high-throughput model of infection using larvae of Galleria mellonella, an invertebrate used to study host-pathogen interactions for a wide range of microbial species. We demonstrate that P. destructans can kill G. mellonella larvae in an inoculum-dependent manner when infected larvae are housed at 13°C or 18°C. Larval killing is an active process, as heat-killed P. destructans spores caused significantly decreased levels of larval death compared to live spores. We also show that fungal spores that were germinated prior to inoculation were able to kill larvae 3-4 times faster than non-germinated spores. Lastly, we identified chemical inhibitors of P. destructans and used G. mellonella to evaluate these inhibitors for their ability to reduce virulence. We demonstrate that two chemicals, trifluoperazine and amphotericin B, can effectively block larval killing by P. destructans and thereby establish that this infection model can be used to screen biocontrol agents against this fungal pathogen.peer-reviewed)

We utilize a multi-omics approach to demonstrate that diets supplemented with oats, a rich source of microbiota-accessible carbohydrates, are able to confer protection against antibiotic-induced dysbiosis (AID). Our findings affirm that not only is host diet important in shaping antibiotics effects on gut microbiome composition and function but also that the timing of these diets may play an even greater role in managing AID.