Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSunexpectedly found to be important for both sex-induced and vegetative silencing. The nine remaining missing genes are being tested for roles in bothsex-induced and mitotic silencing (SIS, MIS).244. A chemical-genetic map of a human fungal meningitis pathogen. Jessica C. S. Brown 1 , Benjamin VanderSluis 2 , Raamesh Deshpande 2 , Arielle Butts 3 ,Sarah Kagan 4 , Itzhack Polacheck 4 , Damian J. Krysan 3 , Chad L. Myers 2 , Hiten D. Madhani 1 . 1) Biochemistry and Biophysics, U. California, San Francisco, SanFrancisco, CA; 2) Computer Science and Engineering, U. Minnesota, Minneapolis, MN; 3) Pediatrics, U. Rochester Medical Center, Rochester, NY; 4) ClinicalMicrobiology and Immunology, Tel Aviv University, Tel Aviv, Israel.The systematic profiling of the impact of small molecules on the growth rate of gene deletion mutants is termed chemogenomic profiling. This approachbeen extensively used in model organisms, primarily baker’s yeast, to functionally annotate genes and to obtain insights into mode-of-action (MOA) forchemical compounds (1). Here we describe the application of systematic chemical-genetics a significant human pathogen. Cryptococcus neoformans is anopportunistic basidiomycetes pathogen responsible for lethal meningitis in immunocompromised patients. Current therapies are inadequate due to apaucity of drugs and a poor understanding of pathogenesis. Our laboratory previously constructed a partial gene deletion collection and used it to identifynumerous genes required for infection as well as for the production of virulence factors (2). This work identified numerous novel infectivity genes, butmany did not have an identifiable molecular function. We have now used chemogenomic profiling to both bridge this gap in gene annotation and to obtaininsights into drug MOA. To accomplish this goal, we identified and utilized over 200 diverse chemical compounds that impact pathogen growth to create aunique phenotypic signature for ~1500 C. neoformans gene deletion strains. We used colony arrays, robotics, automated image analysis, and extensivedata normalization algorithms to analyze several million phenotypic measurements. We used these data to identify clusters of genes and compounds withrelated patterns of chemical-genetic interactions. Our analysis identified virulence genes that act through related mechanisms. For example, one gene setinvolves a number predicted to be involved in histone modification. Members of a second set of genes are required in production of the C. neoformanspolysaccharide capsule, a well-established virulence factor. We have also obtained new insights into the MOA of several antifungal compounds. TheCryptococcus chemical-genetic map will be a valuable resource for functional annotation of the genome of this meningitis pathogen, characterization ofnew drug targets, and the identification lead compounds for antifungal drug development.1. Hillenmeyer et al., Science 320 (2008). 2. Liu et al., Cell 135 (2008).245. Whole genome sequencing of high-mortality and low-mortality strains of Cryptococcus neoformans var. grubii to discover genetic determinants ofvirulence. Tami R. McDonald, Kirsten Nielsen. Department of Microbiology, University of Minnesota, Minneapolis, MN.In sub-Saharan Africa, meningitis caused by the fungus Cryptococcus neoformans var. grubii is a major cause of AIDS-related mortality. To investigate therole of fungal genotype in clinical disease, we sequenced 8 genes for 503 clinical isolates of Cryptococcus neoformans var. grubii. A phylogenetic analysis ofthese strains demonstrated that 501 isolates were VNI strains. Haplotype network analysis revealed three major groups (BURST groups 1 - 3). Patientmortality was associated with fungal strain genotype, with strains in BURST group 3 demonstrating low mortality. Whole genome sequencing of 13representative genotypes revealed SNPs unique to the high mortality strains, and SNPs unique to the low-mortality strains, pointing to possible targets forfuture gene deletion and allele swap experiments to determine the role of the genes in pathogenesis.246. Identification of high temperature-regulated genes controlled by Sch9 through comparative transcriptome analysis in Cryptococcus neoformans.Dong-Hoon Yang 1 , Kwang-Woo Jung 1 , Jang-Won Lee 1 , Min-Hee Song 1 , Anna Floyd 2 , Joseph Heitman 2,3 , Yong-Sun Bahn 1 . 1) Biotechnology Dept, YonseiUniversity, Seoul, South Korea; 2) Departments of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA; 3)Departments of Medicine, and Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA.Adaptation to temperature changes is one of crucial virulence factors for Cryptococcus neoformans during host infection. In the human fungal pathogen,diverse signal transduction pathways, such as Ras/Cdc24, calmodulin/calcineurin, Mpk1 and Hog1 MAPK pathways, are involved in the temperatureadaptation process. In addition to the pathways, the Sch9 protein kinase has been implicated in thermotolerence of C. neoformans, but its regulatorymechanism remains elusive. In this study we aimed to identify Sch9-dependent or -independent temperature-regulated genes in a genome scale and toelucidate the regulatory mechanism of Sch9 in thermotolerance of C. neoformans. For this purpose, we performed comparative transcriptome analysiswith the wild type serotype A H99 strain and sch9D mutant during temperature upshift from 25°C to 37°C or 40°C. The temperature upshift caused a globalscale of remodeling in gene expression profiles (1872 genes, P