Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSSaccharomyces cerevisiae Hrb1/Gbp2, nonessential shuttling mRNA binding proteins belonging to the SR (Serine-Arginine Rich) and RRM (RNA RecognitionMotif) protein family. snxA hrb1 is nonessential, its deletion phenocopies the snxA1 mutation, and overexpression of gDNAs or of alternatively spliced snxAcDNAs rescues snxA1 mutant phenotypes. SNXA HRB1 is predominantly nuclear, but is not retained in the nucleus during the partially-closed mitosis of A.nidulans. We further demonstrate that the snxA1 mutation does not suppress nimX2 by altering NIMX2 CDC2 /NIME CYCLINB kinase activity, suggesting that theeffects of SNXA1 on NIMX2 CDC2 /NIME CYCLINB may be due to altered localization of NIME CYCLINB . These data suggest a novel role in G2/M regulation for thisSR/RRM family member. This work was supported by the Mississippi INBRE funded by grants from the National Center for Research Resources(5P20RR016476-11) and the National Institute of General Medical Sciences (8 P20 GM103476-11) from the National Institutes of Health.79. The Aspergillus nidulans MAPK module AnSte11-Ste50-Ste7-Fus3 controls development and secondary metabolism. Oezguer Bayram 1* , OezlemSarikaya Bayram 1 , Yasar Luqman Ahmed 2 , Jun-Ichi Maruyama 1,4 , Oliver Valerius 1 , Silvio Rizzoli 3 , Ralf Ficner 2 , Stefan Irniger 1 , Gerhard Braus 1 . 1) Institute ofMicrobiology & Genetics, Department of Molecular Microbiology and Genetics, Georg-August-Universität, Grisebachstr. 8, D 37077 Goettingen, Germany;2) Department of Molecular Structural Biology, Institute for Microbiology and Genetics, Georg-August-Universität, Goettingen; 3) European NeuroscienceInstitute, Deutsche Forschungsgemeinschaft Center for Molecular Physiology of the Brain/Excellence Cluster 171, 37077 Göttingen; 4) Department ofBiotechnology, The University of Tokyo, Tokyo, Japan.The sexual Fus3 MAP kinase module of yeast is highly conserved in eukaryotes and transmits external signals from the plasma membrane to the nucleus.We show here that the module of the filamentous fungus Aspergillus nidulans (An) consists of the AnFus3 MAP kinase, the upstream kinases AnSte7 andAnSte11, and the AnSte50 adaptor. The fungal MAPK module controls the coordination of fungal development and secondary metabolite production. Itlacks the membrane docking yeast Ste5 scaffold homolog but similar to yeast the entire MAPK module interacts with each other at the plasma membrane.AnFus3 is the only subunit with the potential to enter the nucleus from the nuclear envelope. AnFus3 interacts with the conserved nuclear transcriptionfactor AnSte12 to initiate sexual development and phosphorylates VeA which is a major regulatory protein required for sexual development andcoordinated secondary metabolite production. Our data suggest that not only Fus3 but even the entire MAPK module complex of four physicallyinteracting proteins can migrate from plasma membrane to nuclear envelope.80. Functional analysis of sterol transporter in filamentous fungus Aspergillus nidulans. Nicole Bühler, R. Fischer, N. Takeshita. Microbiology, KarlsruheInstitut of Technology, Karlsruhe, Germany.A continuous flow of secretion vesicles from the hyphal cell body to the growing hyphal tip provides the delivery of proteins and lipids to the tip and isessential for cell wall and cell membrane extension at the tip. Apical sterol-rich plasma membrane domains (SRDs), which can be viewed using the sterolbindingfluorescent dye filipin, are gaining attention for their important roles in polarized growth of filamentous fungi. Although the importance of SRDs isbecoming clear, their exact roles and formation mechanisms remain rather unclear. Transport of sterol to hyphal tips is thought to be important for theSRDs organization. Oxysterol binding proteins, which are conserved from yeast to human and involved in vesicular trafficking, signalling, lipid metabolismand non-vesicular sterol transport. Saccharomyces cerevisiae has seven oxysterol binding protein homologues (OSH1-7). Their subcellular distributions areregulated respectively. The OSH proteins are thought to function as a sterol transporter between closely located membranes independently of vesicletransport. In the filamentous fungus Aspergillus nidulans, we found five OSH genes. To investigate their functions for the polarized growth and SRDsorganization, their localization are analyzed by GFP tagging. The gene-deletion strains are constructed and analyzed. Their expression levels are analyzedvia qRT-PCR.81. Mechanisms of cellular resistance to copper and arsenic in Aspergillus nidualans. Steven H. Denison. Natural Sciences, Eckerd College, St Petersburg,FL.Copper is an essential element for cells that is toxic in high concentrations. Understanding cellular mechanisms for survival in high concentrations ofcopper is important for at least two reasons. Firstly, copper is an important environmental contaminant. In addition, two human genetic disorders, Wilsonand Menkes diseases, result from impaired copper transport. I am using the filamentous fungus, Aspergillus nidulans, as a model organism forunderstanding cellular mechanisms of resistance to high concentrations of copper. I identified a gene in A. nidulans homologous to the coppertransporting ATPase-encoding genes mutated in Wilson and Menkes diseases. To determine the location of this copper transporter in A. nidulans cells, Iused fusion PCR to construct a GFP-tagged version of the gene, which was then transformed into A. nidulans in a gene replacement. In terms of its locationin the cell, the A. nidulans GFP-tagged protein behaves in the same way as the Menkes disease protein: it is located to an intracellular compartment(possibly the Golgi, as in human cells) in low copper medium but appears in the plasma membrane upon addition of excess copper to the medium. Inaddition, disruption of the A. nidulans copper transporter gene results in increased sensitivity to copper in the growth medium relative to wild type cellsand cells expressing the GFP-tagged protein. Taken together, these data suggest that the transporter functions in the plasma membrane in high copperenvironments to remove excess copper from cells. Arsenic is also an important environmental contaminant. To begin to understand the mechanism ofarsenic resistance in A. nidulans cells, I have GFP-tagged and disrupted a putative arsenic transporter gene from A. nidulans. Disruptants are more sensitiveto arsenic than wild type cells and cells expressing the GFP-tagged protein. The GFP fusion protein localizes to the plasma membrane, consistent with afunction for the protein in transporting arsenic across the plasma membrane, removing arsenic from cells.82. Functional characterization of Aspergillus nidulans ANID_05595.1: a possible homologue of the polarisome component Pea2. Nathan W Gross,Bradley Downs, Steven D Harris. Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588-0660.Cell polarity is a defining feature of filamentous fungal growth. However, the complete molecular pathway that regulates this morphogeneticcharacteristic has not yet been elucidated. In Aspergillus nidulans, a germ tube emerges from a discrete location along the conidium following a briefperiod of isotropic swelling. Plasma membrane and cell wall components are continuously added to the apex of the germ tube via microtubule and actinmediated trafficking of vesicles to this region. As growth progresses, germ tube cells undergo cytokinesis and are compartmentalized by septa.Additionally, the cell wall becomes increasingly cross-linked throughout subapical regions forming a hypha, which continues to grow in the same polarizedmanner. ANID_05595.1 is located on chromosome 5, contig 96, and encodes a 946 amino acid hypothetical involucrin repeat protein. To investigate thefunction of ANID_05595.1 in A. nidulans, deletion mutants were generated using pyrG from Aspergillus fumigatus as a selectable marker. This mutationresulted in restricted colony growth, increased hyphal diameter, and dichotomous hyphal branching patterns. These phenotypes suggest thatANID_05595.1 function is important to the maintenance of polarized cell growth in A. nidulans and other ascomycetes. The hypothetical ANID_05595.1protein shares characteristics with Saccharomyces cerevisiae Pea2, a polarisome component required for bipolar budding and mating. Along withstructural similarities, the phenotypes observed in S. cerevisiae DPea2 are similar to A. nidulans D5595. This suggests that ANID_05595.1 may perform asimilar mechanistic function to Pea2 in A. nidulans.27th Fungal Genetics Conference | 141