Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTS398. UVE1 is a Photo-regulated Gene Required for the Protection of Mitochondrial DNA in Cryptococcus neoformans from UV Induced DNA Damage.Surbhi Verma, Alexander Idnurm. School Of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110.The UVE1 gene is an apurinic/apyrimidinic endonuclease, identified in a T-DNA insertion mutagenesis screen in the pathogenic fungus Cryptococcusneoformans. UVE1 mutation or deletion leads to a UV hypersensitive phenotype. The homologous gene in fission yeast Schizosaccharomyces pombeencodes apurinic/apyrimidinic endonuclease acting in the UVDE-dependent excision repair (UVER) pathway. C. neoformans UVE1 complements a S.pombe uvde knockout strain, hence functionally similar. In Cryptococcus, the Bwc1-Bwc2 photoreceptor complex regulates mating, virulence andultraviolet radiation (UV) stress tolerance. How the Bwc1-Bwc2 complex regulates these functions is not clear. We discovered that UVE1 is photoregulatedin Bwc1-Bwc2 dependent manner in Cryptococcus, and in Neurospora crassa and Phycomyces blakesleeanus that represent two other major lineages inthe fungi. Overexpression of UVE1 in bwc1 mutants rescues their UV sensitivity phenotype and gel mobility shift experiments show binding of Bwc2 to theUVE1 promoter. These experiments indicate that UVE1 is a direct downstream target for the Bwc1-Bwc2 complex, required for UV stress tolerance. Uve1-GFP fusions localize to the mitochondria in C. neoformans. Hence in Cryptococcus, UVE1 is a key photo-regulated gene responsible for tolerance to UVstress for protection of the mitochondrial genome.399. Uve1 endonuclease protects Cryptococcus neoformans from UV damage through regulation by the White collar complex. Surbhi Verma, AlexanderIdnurm. School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO.In Cryptococcus neoformans the Bwc1-Bwc2 photoreceptor complex regulates mating, virulence and ultraviolet radiation (UV) stress tolerance. Weidentify and characterize a gene, UVE1, whose mutation leads to a UV hypersensitive phenotype. The homologous gene in Schizosaccharomyces pombeencodes a apurinic/apyrimidinic endonuclease acting in the UVDE-dependent excision repair (UVER) pathway. C. neoformans UVE1 complements a S.pombe uvde knockout strain. UVE1 is photoregulated, in a Bwc1-dependent manner in Cryptococcus, as well as in Neurospora crassa and Phycomycesblakesleeanus. Overexpression of UVE1 in bwc1 mutants rescues their UV sensitivity phenotype and gel mobility shift experiments show binding of Bwc2to the UVE1 promoter, indicating that UVE1 is a direct downstream target for the Bwc1-Bwc2 complex. Uve1-GFP fusions localize to the mitochondria. InC. neoformans UVE1 is a key gene regulated in response to light that is responsible for tolerance to UV stress for protection of the mitochondrial genome.400. Multiple laccase genes in Schizophyllum commune. S. Madhavan, K. Krause, E. Kothe. Microbiology Microbial Communication, Friedrich SchillerUniversity, Jena, Germany 07743.The saprophytic white rot fungus S. commune, is involved in the degradation of complex organic molecules including lignin as well as refractory organicmatter from black slate with the help of different exoenzymes. Thus, the genome sequence of S. commune was used to gain an insight into the functionalanalysis of laccases and laccase-like enzymes. Laccases are multi-copper oxidases that catalyze oxidation of a wide spectrum of organic and inorganicsubstances. In most fungi, laccases are found to be multigene families producing isoenzymes with multiple functions. Two laccases and four laccase-likegenes have been identified from the genome of S. commune. Differential regulation of individual genes was analysed at the transcript level by quantitativereal-time PCR. Individual laccase genes showed distinct expression profiles during fungal development, morphogenesis and during substrate utilization.Genes lcc1 and lcc4 seem to play a role during the primordial formation for fruiting bodies phase and lcc2 and lcc6 were found to be related to thedikaryotic phase and vegetative growth. Gene lcc5 is regulated during fruitbody formation. Various stress responsive elements (XRE, STRE) could bedetected in all respective promoters indicating an infuence of aromatic compounds and stress molecules in transcriptional regulation. Characterization oflaccase mutants with respect to organic matter and black slate degradation is linking these data to different functions of single laccase and laccase-likegenes.401. Regulation of DNA repair genes expression by UV stress in Neurospora crassa. Tsukasa Takahashi, Makoto Fujimura, Akihiko Ichiishi. Faculty of LifeScience, Toyo University, Ora-gun, Gunma, Japan.In all organisms, DNA is constantly damaged by endogenous and exogenous factors such as environments and chemicals. In these genotoxins, ultraviolet(UV) irradiation induces DNA damage such as cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs). N.crassa has three mechanisms torepair UV-damaged DNA; nucleotide excision repair (NER), UV dependent repair (UVDR), photoreactivation (PR). Because UV-induced DNA lesions areefficiently removed by these DNA repair systems, N.crassa shows highly resistance to UV as compared to other species. In human and S.cerevisiae, it hasbeen reported that some of DNA repair genes involved in removal of UV-damaged DNA were induced by UV irradiation. Furthermore, some MAP kinasepathways were activated in response to UV irradiation in human. In N.crassa, characterizations of DNA repair gene mutants have been performed in detail,but relationship between expression of these genes and UV stress are not clear yet. Thus, we investigated whether UV stress is involved in regulation ofexpression of DNA repair genes, and whether UV stress activates MAP kinase pathway like a human. We show that some DNA repair genes such as mus-40, mus-43 were up-regulated by UV irradiation. The OS-2 MAP kinase, involved in response to osmotic stress in N.crassa, was activated by UV irradiation,and then expression of mus-40, mus-43 were not induced after UV irradiation in os-2 mutant. In addition, os-2 mutant was more sensitive to UV irradiationthan the wild-type. These data suggest that UV stress upregulates some DNA repair genes and UV signal was partially transmitted by OS MAP kinasecascade, in N.crassa.402. Diverse classes of small RNAs originating from genomic hotspots, tRNA and the mitochondrial genome in Phytophthora infestans. Sultana N.Jahan 1 , Anna K. M. Åsman 1 , Ramesh R. Vetukuri 1 , Anna O. Avrova 2 , Stephen C. Whisson 2 , Christina Dixelius 1 . 1) Department of Plant Biology and ForestGenetics, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, PO-Box 7080, SE-75007, Uppsala, Sweden;2) Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom.Phytophthora infestans is the oomycete pathogen responsible for the devastating late blight disease on potato and tomato. P. infestans is notorious forits ability to evolve to overcome resistant potato varieties. The genome of this pathogen has been sequenced and revealed vast numbers of transposonsequences, and hundreds of disease-promoting effector proteins. We are aiming at understanding gene-silencing mechanisms in P. infestans includingdeciphering roles of small non-coding RNAs. In our previous work we have shown that P. infestans has an active RNA silencing pathway (Vetukuri et al.2011). We also performed deep sequencing of sRNAs from P. infestans and knocked down the genes encoding the RNA silencing components Argonauteand Dicer in order to investigate their roles in sRNA biogenesis (Vetukuri et al. 2012). Here, we describe the distribution of genomic sites from which sRNAsoriginate. Genome-wide analysis of sRNAs revealed diverse classes mapping to genomic sources such as tRNAs, rRNAs, genomic sRNA ‘hotspots’, and themitochondrial genome. Most tRNA-derived RNA fragments (tRFs) mapped to the sense strand of the 5’-halves of mature tRNAs and peaked at 27 and 30 ntlengths. In accordance with reports from other organisms (Franzén et al. 2011), the tRFs mapped to different tRNA isoacceptors with unequal frequencies,the Ile_tRNA_Cluster_0 showing the highest proportion of mapping sRNAs. We are presently using our Dicer knockdown transformants to investigate thetRF biogenesis mechanism. Another interesting group of sRNAs are those that map to transposons that have close-by neighboring RXLR-effector genes.27th Fungal Genetics Conference | 219