dictyNews Electronic Edition Volume 37, number 3 July 29, 2011 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu or by using the form at http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. Back issues of dictyNews, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. Follow dictyBase on twitter: http://twitter.com/dictybase ========= Abstracts ========= BzpF is a CREB-like transcription factor that regulates spore maturation and stability in Dictyostelium Eryong Huang, Shaheynoor Talukder, Timothy R. Hughes, Tomaz Curk, Blaz Zupan, Gad Shaulsky and Mariko Katoh-Kurasawa Developmental Biology, in press The cAMP response element-binding protein (CREB) is a highly conserved transcription factor that integrates signaling through the cAMP-dependent protein kinase A (PKA) in many eukaryotes. PKA plays a critical role in Dictyostelium development but no CREB homologue has been identified in this system. Here we show that Dictyostelium utilizes a CREB-like protein, BzpF, to integrate PKA signaling during late development. bzpFÐ mutants produce compromised spores, which are extremely unstable and germination defective. Previously, we have found that BzpF binds the canonical CRE motif in vitro. In this paper, we determined the DNA binding specificity of BzpF using protein binding microarray (PBM) and showed that the motif with the highest specificity is a CRE-like sequence. BzpF is necessary to activate the transcription of at least 15 PKA-regulated, late-developmental target genes whose promoters contain BzpF binding motifs. BzpF is sufficient to activate two of these genes. The comparison of RNA sequencing data between wild type and bzpFÐ mutant revealed that the mutant fails to express 205 genes, many of which encode cellulose-binding and sugar-binding proteins. We propose that BzpF is a CREB-like transcription factor that regulates spore maturation and stability in a PKA-related manner. Submitted by: Mariko Katoh-Kurasawa [mkatoh@bcm.edu] -------------------------------------------------------------------------------- Dictyostelium transfer RNA gene-targeting retrotransposons: Studying mobile element-host interactions in a compact genome Thomas Winckler, Jana Schiefner, Thomas Spaller, Oliver Siol UniversitŠt Jena, Institut fŸr Pharmazie, Lehrstuhl fŸr Pharmazeutische Biologie, Semmelweisstrasse 10, 07743 Jena, Germany Mobile Genetic Elements, in press The model species of social amoebae, Dictyostelium discoideum, has a compact genome consisting of about two thirds protein-coding regions, with intergenic regions that are rarely larger than 1,000 bp. We hypothesize that the haploid state of D. discoideum cells provides defense against the amplification of mobile elements whose transposition activities would otherwise lead to the accumulation of heterozygous, potentially lethal mutations in diploid populations. We further speculate that complex transposon clusters found on D. discoideum chromosomes do not a priori result from integration preferences of these transposons, but that the clusters instead result from negative selection against cells harboring insertional mutations in genes. D. discoideum cells contain a fraction of retrotransposons that are found in the close vicinity of tRNA genes. Growing evidence suggests that these retrotransposons use active recognition mechanisms to determine suitable integration sites. However, the question remains whether these retrotransposons also cause insertional mutagenesis of genes, resulting in their enrichment at tRNA genes, which are relatively safe sites in euchromatic regions. Recently developed in vivo retrotransposition assays will allow a detailed, genome-wide analysis of de novo integration events in the D. discoideum genome. Submitted by: Thomas Winckler [t.winckler@uni-jena.de] -------------------------------------------------------------------------------- Phylogeny-wide analysis of social amoeba genomes highlights ancient origins for complex intercellular communication. Andrew J. Heidel, Hajara M. Lawal, Marius Felder, Christina Schilde, Nicholas R. Helps, Budi Tunggal, Francisco Rivero, Uwe John, Michael Schleicher, Ludwig Eichinger, Matthias Platzer, Angelika A. Noegel, Pauline Schaap, Gernot Gloeckner Genome Research, in press Dictyostelium discoideum (DD), an extensively studied model organism for cell and developmental biology, belongs to the most derived group 4 of social amoebas, a clade of altruistic multicellular organisms. To understand genome evolution over long time periods and the genetic basis of social evolution, we sequenced the genomes of Dictyostelium fasciculatum (DF) and Polysphondylium pallidum (PP), that represent the early diverging groups 1 and 2, respectively. In contrast to DD, PP and DF have conventional telomere organisation and strongly reduced numbers of transposable elements. The number of protein coding genes is similar between species, but only half of them comprise an identifiable set of orthologous genes. In general, genes involved in primary metabolism, cytoskeletal functions and signal transduction are conserved, while genes involved in secondary metabolism, export and signal perception underwent large differential gene family expansions. This most likely signifies involvement of the conserved set in core cell and developmental mechanisms, and of the diverged set in niche- and species-specific adaptations for defence and food, mate and kin selection. Phylogenetic dating using a concatenated data set and extensive loss of synteny indicate that DF, PP and DD split from their last common ancestor at least 0.6 billion years ago. Submitted by Gernot Gloeckner [gloeckner@igb-berlin.de] ============================================================== [End dictyNews, volume 37, number 3]