Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSnatural products. To date, only a dozen gene clusters could be matched to the requisite PKS-NRPS pathways and the programming of the multifunctionalenzymes is still enigmatic. The (heterologous) expression of chimeras of PKS (lovastatin synthase, LovB) and NRPS (cytochalasin synthetase, CheA) inAspergillus terreus did not result in the production of polyketide-amino acid hybrid molecules and suggests a potential incompatibility of a fungal highlyreducing PKS (hrPKS) with the NRPS component of fungal PKS-NRPS hybrids. Furthermore, the heterologous expression of a shortened CheA (truncatedafter the C domain) in A. oryzae did not lead to cyclized products. To rationalize the unexpected outcome of the gene fusion (and shortening) experiments,we accomplished extensive bioinformatic analyses of fungal PKS-NRPS hybrids and LovB-type PKS. Hence, a noncanonical function of C-terminalcondensation (C) domains in truncated PKS-NRPS homologues and an evolutionary imprint of the PKS-NRPS domains, which reflect the evolutionaryhistory of the entire megasynthase, was inferred. Moreover, the participation of not only the adenylation (A) domain but also the C domain to amino acidselection was shown to be likely. These findings shed new light on the complex code of this emerging class of multifunctional enzymes and will greatlyfacilitate future combinatorial biosynthesis and pathway engineering approaches towards natural product analogues.726. Secondary metabolism and development is mediated by LlmF control of VeA subcellular localization in Aspergillus nidulans. Jonathan M. Palmer 1 ,Jeffrey Theisen 1 , Rocio Duran 2 , Scott Grayburn 2 , Ana Calvo 2 , Nancy Keller 1 . 1) Medical Microbiology and Immunology, Univ Wisconsin, Madison, WI; 2)Biological Sciences, Northern Illinois University, DeKalb, IL.Secondary metabolism and development are linked in Aspergillus through the conserved regulatory velvet complex composed of VeA, VelB and LaeA.The founding member of the velvet complex, VeA, shuttles between the cytoplasm and nucleus in response to alterations in light. Here we describe a newinteraction partner of VeA identified through a reverse genetics screen looking for LaeA-like methyltransferases in Aspergillus nidulans. One of the putativeLaeA-like methyltransferases identified, LlmF, is a negative regulator of sterigmatocystin production and sexual development. LlmF interacts directly withVeA and the repressive function of LlmF is mediated by influencing the localization of VeA, as over-expression of llmF decreases the nuclear to cytoplasmicratio of VeA while deletion of llmF results in an increased nuclear accumulation of VeA. We show that the methyltransferase domain of LlmF is required forfunction, however LlmF does not directly methylate VeA in vitro. This study identifies a new interaction partner for VeA and highlights the importance ofcellular compartmentalization of VeA for regulation of development and secondary metabolism.727. Overproduction of phleichrome by synthetic inducers and cloning of polyketide synthase genes in phytopathogenic fungus Cladosporium phlei. K.-K. So 1 , N.-L. Nguyen 1 , J.-M. Kim 2 , Y.-S. Jang 1 , Y.-S Jeong 1 , D.-H. Kim 1 . 1) Institute for Molecular Biology and Genetics, Center for Fungal pathogenesis,Chonbuk National University, Jeonju, Jeonbuk, South Korea; 2) Department of Bio-Environmental Chemistry, Wonkwang University, Iksan, Jeonbuk, SouthKorea.Phleichrome pigment produced by a Cladosporium phlei is a pathogenic toxin of timothy plant (Phleum pretense). Phleichrome reacts with oxygenmolecules following light activation to produce highly toxic reactive oxygen species. Phleichrome is structurally similar to elsinochrome and several other4,9-dihydroxyperylene-3,10-quinone fungal toxins. Phleichrome has a huge potential to be used as photodynamic agent for treatment of cancer and viralinfection. Using the UV mutagenesis method we were able to obtain two mutant strains that overproduced phleichrome in different culture conditionscompared with the wild type strain. In addition, we synthesized two different diketopiperazines as inducers and confirmed that diketopiperazinessignificantly enhanced phleichrome biosynthesis in a dose dependent manner. To gain insight into the metabolic pathway of phleichrome production, weperformed to clone and sequence several polyketide synthase (PKS) genes. Among the three representative types of PKS, two, one, and one gene forreducing-, partially reducing-, and non-reducing type PKS, respectively, were cloned, sequenced, and characterized. Biological characterization of thesegenes is underway to determine its role in the production of phleichrome and open the possibility of metabolically engineering this pathway foroverproduction of the desired substance.728. Symbiotic fungal endophytes that confer tolerance for plant growth in saline soil. Zakia Boubakir, Elizabeth Cronin, Susan GW Kaminskyj. Biology,Univ Saskatchewan, Saskatoon, Saskatchewan, Canada.Fungal endophytes are plant symbionts, and appear to be ubiquitous in plants growing in natural soils. Pioneering work by RS Redman and RJ Rodriguezshowed that class II fungal endophytes confer tolerance to harsh growth environments. These endophyte strains are expected to enhance plant growthand improve nutrient uptake under normal and saline conditions, although currently the mechanism(s) is unknown. Soil salinity is one of the most seriousagricultural problems that restrict plant growth and crop yield in many areas of the world. Saskatchewan has large areas of salinized soils as well as manysaline lakes. In this study, we are characterizing endophyte fungi isolated from salinized soils in southern Saskatchewan. These include potash minetailings, which are ~ 95 % NaCl. In the spring of 2012 we collected 90 plant samples from 9 sites, from which we isolated ~450 endophyte fungi. Here, wewill present a preliminary characterization of isolate Skj422.08. This strain has been shown to confer NaCl tolerance for tomato and wheat that weregrown in soil mix watered with fresh water, then stressed with 200 mM or12 g/L NaCl (tomato), or 300 mM or 18g/L NaCl (wheat). Skj422.08 alsoimproved growth when tomato and wheat were grown from seed in 150 mM or 9 g/L NaCl. This project is funded in part by Mosaic Co, a major producerof potash in Saskatchewan, as well as phosphate and micronutrients in other parts of North America, and worldwide.729. Stable cesium and radiocesium response of Schizophyllum commune. Matthias Gube 1 , Alix Günther 2 , Flemming Katrin 2 , Linde Jörg 3 , Raff Johannes 2 ,Kothe Erika 1 . 1) Microbial Communication, Institute for Microbiology, Friedrich Schiller University of Jena, Thuringia, Germany; 2) Helmholtz-CentreDresden-Rossendorf, Germany; 3) Hans-Knöll-Institute for Natural Product Research, Jena, Germany.Radioisotope contamination poses a threat to both ecosystem functioning and public health. Compared with plants, fungi can accumulate much higheramounts of heavy metals and radionuclides in their fruiting bodies. This was seen after the reactor accident of Chernobyl in 1986, when it became clearthat fungal uptake of radionuclides such as 60Co, 90Sr, and most importantly 137Cs may reach harmful levels if consumed. It is thus of crucial importanceto study radionuclide uptake into fungi to evaluate subsequent migration in the environment, thus allowing for meaningful ecotoxicological riskassessment. Usually, this is being performed by analysing stable isotopes of the same elements, whenever these are available. Due to their lowercriticality, this reduces costs and risk of associated experiments. It is generally assumed that the effects of both are identical. However, comparativeanalyses have seldom been performed, and never with fungi. Ionizing radiation is known to cause effects ranging from DNA and Protein damage toincreased oxidative stress and possibly apoptosis in a number of organisms. Especially in gene expression studies, certain reactions such as regulation ofprotein and nucleic acid repair mechanisms might thus deviate between stable and radioisotope exposure. Thus, differential gene expression of the fullysequenced model organism S. commune was analysed using MACE (Massive Analysis of CDNA Ends) under treatment with stable 133Cs and the b-decaying 137Cs and compared with untreated samples. Differential gene expression analysis points out factors responding to either radiation or Cs ions,thus differentiating between metal ion stress and radiation effects. While several carbohydrate metabolism genes and especially hydrophobin genes arespecifically regulated following radiation, most expected responding factors, such as genes involved in stress response or ion and water transport, are27th Fungal Genetics Conference | 299