Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTS342. Functional Analysis of Genes in Regions of Introgression in Coccidioides. Bridget M. Barker. Immunology & Infectious Diseases, Montana State Univ,Bozeman, MT.Coccidioides immitis and C. posadasii are dimorphic fungi endemic to the Americas. Genomic analysis of sequenced strains of C. posadasii and C. immitisreveals insights into the population biology of these organisms. There is strong evidence for hybridization and introgression, such that for many of the C.immitis strains, there are several regions that have a closer match to C. posadasii, but few regions within C. posadasii matching C. immitis. Multiplehybridization regions were located in several genomes analyzed, and at least one region containing ten genes exhibits a pattern consistent withintrogression in C. immitis. This conserved region was further evaluated in a larger collection of isolates. Approximately half of the C. immitis isolatescontain the C. posadasii fragment, and the majority of those are from the southern California and Mexico populations. The region of introgressionrepresents a unique opportunity to functionally assess genes that are likely to be relevant for species-specific virulence and adaptation to mammalianhosts or the environment. This region has a shared recombination point flanking a metalloproteinase, Mep4; genes that are highly expressed in theparasitic phase; and genes of unknown function. Importantly, evolutionary selection has preserved this region in multiple strains of C. immitis furtheremphasizing the possible role in virulence of these genes. Variation among strains for virulence in murine models of coccidioidomycosis has beenobserved, but has not been tested in the context of the newly discovered species or with a targeted underlying genetic mechanism hypothesis to test.Gene deletion mutants are being generated for three genes in the conserved introgression region to determine effects on in vitro growth andmorphological change under host relevant conditions.343. Classification and accurate functional prediction of carbohydrate-active enzymes by recognition of short, conserved peptide motifs. Peter K. Busk,Lene Lange. Biotechnology and Chemistry, Aalborg University, AAU Cph, Copenhagen, Copenhagen, Denmark.Functional prediction of carbohydrate-active enzymes is difficult due to low sequence identity hampering recognition of the functional relationship.However, similar enzymes often share a few short motifs, e.g., around the active site even when the overall sequences are very different. To exploit thisnotion for functional prediction of carbohydrate-active enzymes we developed a simple algorithm, Peptide Pattern Recognition (PPR) that can divideproteins into groups of sequences that share a set of short conserved sequences. When this method was used on 118 functionally characterized GH5proteins with 9 % average pairwise identity and representing four enzymatic functions, 97 % of the GH5 proteins were sorted into groups correlating withtheir enzymatic activity. Furthermore, we analyzed 8138 GH13 proteins including 204 experimentally characterized enzymes with 28 different functions.There was a 91 % correlation between group and enzyme activity. These results indicate that the function of carbohydrate-active enzymes can bepredicted with high precision by finding short conserved motifs in their sequences. The GH61 family is important for fungal biomass conversion but onlyfew GH61s have been functionally characterized. Interestingly, PPR divided 743 GH61 proteins into 16 subfamilies useful for targeted investigation of thefunction of these proteins, and pinpointed three conserved motifs with putative importance for enzyme activity. The conserved sequences were useful fordiscovery and cloning of new, subfamily-specific GH61 proteins from 14 different fungi. In conclusion, identification of conserved sequence motifs is a newapproach to sequence analysis that can predict carbohydrate-active enzyme functions with high precision. Furthermore, these motifs can be used to minegenomes and more complex data such as metagenomes and -transcriptomes for genes encoding proteins with specific, enzymatic activity.344. The mechanism of introner-like element multiplication in fungi. Ate van der Burgt 1 , Edouard Severing 2 , Valeria Ochoa Tufiño 1 , Pierre de Wit 1 , JérômeCollemare 1 . 1) Laboratory of Phytopathology, Wageningen University, Wageningen, Netherlands; 2) Laboratory of Bioinformatics, Wageningen University,6708PB Wageningen, The Netherlands.The recent discovery of introner-like elements (ILEs) in six fungal species shed new light on the origin of regular spliceosomal introns (RSIs). ILEs are novelspliceosomal introns that are found in hundreds of near-identical copies in unrelated genes. They account for the vast majority of intron gains in thesespecies and are not associated with intron losses. Remarkably, ILEs are longer than RSIs and harbor predicted stable secondary structures. However, theyare prone to quickly degenerate in sequence and length to become undistinguishable from RSIs, suggesting that ILEs are predecessors of most RSIs.Further analyses are being performed in order to understand the multiplication mechanism of ILEs, which is hypothesized to resemble the retro-homingmechanism of self-splicing group II introns. The dynamics of ILE’s secondary structures could be predicted and two conserved motifs were identified inalmost all fungal ILEs, which might play an important role in direct insertion into DNA. We also have developed a genetic screen in yeast in order tocapture and characterize ILE insertion events. These ongoing studies should provide hints about the mechanism of ILE multiplication, i.e. how newspliceosomal introns are gained in fungi.345. Fungi use prion folds for signal transduction processes involving STAND proteins. Asen Daskalov, Khalid Salamat, Sven J. Saupe. CNRS, IBGCUMR5095, BORDEAUX, AQUITAINE, France.Prions are proteins embedding genetic information into their structural state. Generally, those proteins exist in a soluble state and sporadically asinfectious amyloid aggregates. Podospora anserina’s [Het-s] is one of the best characterized fungal prions with a remarkably high prevalence in wildpopulations. [Het-s] functions in vegetative incompatibility - a biological process occurring during anastomosis between two genetically incompatiblestrains. The HET-s protein exists in a soluble state - [Het-s*] - or can switch to an aggregated amyloid state - [Het-s] - the prion form. When an [Het-s] prioninfected strain fuses with a strain expressing the alternative allelic variant of the het-s locus - het-S - a cell death reaction of the heterokaryon occurs.Recent studies shed light on the mechanism of [Het-s]/HET-S incompatibility reaction. Differing by 13 amino acids both proteins shares a two domainarchitecture; a globular N-terminal domain called HeLo and a C-terminal Prion Forming Domain (PFD). The latter is able to adopt a b-sheet richconformation with a specific b-solenoid fold. It has been demonstrated that in presence of [Het-s] amyloid fibers HET-S turns into a pore-forming toxin:transconformation of the HET-S PFD by [Het-s] fibers triggers the refolding of the HET-S HeLo domain, inducing the cell death reaction. In an attempt tobetter characterize the conserved features of the [Het-s] b-solenoid fold and identify new distant homologues of HET-S/s, we have generated a minimalconsensus sequence motif of it. Surprisingly, the second best hit in a BLASTp search is in the N-terminal region (3-23) of the product encoded by nwd2, theimmediately adjacent gene to het-S. NWD2 is a STAND protein. STAND proteins form signal transducing hubs through oligomerization upon ligandrecognition. That in mind and several bioinformatics observations led us to propose that HET-S and NWD2 are functional partners in various filamentousfungal species using the amyloid fold in a signal transducing pathway. We will present experimental evidence that NWD2 is able to trigger HET-S toxicity inmuch the same way as [Het-s] does. Further in silico analysis identify a number of these STAND/prion-like gene pairs and suggest that signal transductionthrough an amyloidal prion-like fold is a general widespread mechanism in fungi.346. RNA silencing in poplar anthracnose fungus Colletotrichum gloeosporioides. Simeng Li, Yonglin Wang, Chengming Tian. The Academy of Forestry,Beijing Forestry University, Beijing, China.Poplar anthracnose is one of the most destructive diseases on Poplus sp, whose causal agent is Colletotrichum gloeosporioides. Although the fungus is a27th Fungal Genetics Conference | 205