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Gabriele Marcianò, Stefano Da Vela, Giancarlo Tria, Dmitri I Svergun, Olwyn Byron, Danny T Huang
The histone chaperone complex facilitates chromatin transcription (FACT) plays important roles in DNA repair, replication, and transcription. In the formation of this complex, structure-specific recognition protein-1 (SSRP1) heterodimerizes with suppressor of Ty 16 (SPT16). SSRP1 also has SPT16-independent functions, but how SSRP1 functions alone remains elusive. Here, using analytical ultracentrifugation (AUC) and small-angle X-ray scattering (SAXS) techniques, we characterized human SSRP1 and that from the amoeba Dictyostelium discoideum and show that both orthologs form an elongated homodimer in solution...
May 15, 2018: Journal of Biological Chemistry
Yoshinori Kawabe, Takahiro Morio, Yoshimasa Tanaka, Pauline Schaap
Background: Glycogen synthase kinase 3 (GSK3) regulates many cell fate decisions in animal development. In multicellular structures of the group 4 dictyostelid Dictyostelium discoideum , GSK3 promotes spore over stalk-like differentiation. We investigated whether, similar to other sporulation-inducing genes such as cAMP-dependent protein kinase (PKA), this role of GSK3 is derived from an ancestral role in encystation of unicellular amoebas. Results: We deleted GSK3 in Polysphondylium pallidum , a group 2 dictyostelid which has retained encystation as an alternative survival strategy...
2018: EvoDevo
Wanessa C Lima, Trestan Pillonel, Claire Bertelli, Estelle Ifrid, Gilbert Greub, Pierre Cosson
Klebsiella pneumoniae is an extensively studied human pathogen responsible for a wide variety of infections. Dictyostelium discoideum is a model host organism employed to study many facets of the complex interactions between phagocytic cells and bacteria. Historically, a non-pathogenic strain of K. pneumoniae has been used to feed Dictyostelium amoebae, and more recently to study cellular mechanisms involved in bacterial recognition, ingestion and killing. Here we provide the full genome sequence and functional characterization of this non-pathogenic KpGe strain...
May 10, 2018: Microbes and Infection
Tomokazu Ito, Natsuki Hamauchi, Taisuke Hagi, Naoya Morohashi, Hisashi Hemmi, Yukie G Sato, Tamao Saito, Tohru Yoshimura
In mammals, D-Ser is synthesized by serine racemase (SR) and degraded by D-amino acid oxidase (DAO). D-Ser acts as an endogenous ligand for N -methyl-D-aspartate (NMDA)- and δ2 glutamate receptors, and is involved in brain functions such as learning and memory. Although SR homologs are highly conserved in eukaryotes, little is known about the significance of D-Ser in non-mammals. In contrast to mammals, the slime mold Dictyostelium discoideum genome encodes SR, DAO, and additionally D-Ser specific degradation enzyme D-Ser dehydratase (DSD), but not NMDA- and δ2 glutamate receptors...
2018: Frontiers in Microbiology
R Fredrik Inglis, Odion Asikhia, Erica Ryu, David C Queller, Joan E Strassmann
Interactions between species and their environment play a key role in the evolution of diverse communities, and numerous studies have emphasized that interactions among microbes and among trophic levels play an important role in maintaining microbial diversity and ecosystem functioning. In this study, we investigate how two of these types of interactions, public goods cooperation through the production of iron scavenging siderophores and predation by the social amoeba Dictyostelium discoideum , mediate competition between two strains of Pseudomonas fluorescens that were co-isolated from D...
2018: Frontiers in Microbiology
Philip G Madgwick, Balint Stewart, Laurence J Belcher, Christopher R L Thompson, Jason B Wolf
Contributing to cooperation is typically costly, while its rewards are often available to all members of a social group. So why should individuals be willing to pay these costs, especially if they could cheat by exploiting the investments of others? Kin selection theory broadly predicts that individuals should invest more into cooperation if their relatedness to group members is high (assuming they can discriminate kin from nonkin). To better understand how relatedness affects cooperation, we derived the ‟Collective Investment" game, which provides quantitative predictions for patterns of strategic investment depending on the level of relatedness...
May 7, 2018: Proceedings of the National Academy of Sciences of the United States of America
Aurore Guédin, Linda Yingqi Lin, Samir Armane, Laurent Lacroix, Jean-Louis Mergny, Stéphane Thore, Liliya A Yatsunyk
Guanine-rich DNA has the potential to fold into non-canonical G-quadruplex (G4) structures. Analysis of the genome of the social amoeba Dictyostelium discoideum indicates a low number of sequences with G4-forming potential (249-1055). Therefore, D. discoideum is a perfect model organism to investigate the relationship between the presence of G4s and their biological functions. As a first step in this investigation, we crystallized the dGGGGGAGGGGTACAGGGGTACAGGGG sequence from the putative promoter region of two divergent genes in D...
April 30, 2018: Nucleic Acids Research
Stephanie Cheung, Savrina Manhas, Vivien Measday
Retrotransposons are genetic elements that are similar in structure and life cycle to retroviruses by replicating via an RNA intermediate and inserting into a host genome. The Saccharomyces cerevisiae ( S. cerevisiae ) Ty1-5 elements are long terminal repeat (LTR) retrotransposons that are members of the Ty1- copia ( Pseudoviridae ) or Ty3- gypsy ( Metaviridae ) families. Four of the five S. cerevisiae Ty elements are inserted into the genome upstream of RNA Polymerase (Pol) III-transcribed genes such as transfer RNA (tRNA) genes...
2018: Mobile DNA
Yoko Yamada, Andrew Cassidy, Pauline Schaap
Sporulation in Dictyostelium fruiting bodies evolved from amoebozoan encystation with both being induced by cAMP acting on PKA, but with downstream components still being unknown. Using tagged mutagenesis to find missing pathway components, we identified a sporeless mutant defective in a nuclear protein, SpaA. Expression of prespore genes was strongly reduced in spaA- cells, while expression of many spore stage genes was absent. Chromatin immunoprecipitation (ChIP) of a SpaA-YFP gene fusion showed that (pre)spore gene promoters bind directly to SpaA, identifying SpaA as a transcriptional regulator...
April 27, 2018: Scientific Reports
A F M T Islam, Haicen Yue, Margarethakay Scavello, Pearce Haldeman, Wouter-Jan Rappel, Pascale G Charest
To study the dynamics and mechanisms controlling activation of the heterotrimeric G protein Gα2βγ in Dictyostelium in response to stimulation by the chemoattractant cyclic AMP (cAMP), we monitored the G protein subunit interaction in live cells using bioluminescence resonance energy transfer (BRET). We found that cAMP induces the cAR1-mediated dissociation of the G protein subunits to a similar extent in both undifferentiated and differentiated cells, suggesting that only a small number of cAR1 (as expressed in undifferentiated cells) is necessary to induce the full activation of Gα2βγ...
April 23, 2018: Cellular Signalling
Valentin Pitzen, Sophie Askarzada, Ralph Gräf, Irene Meyer
Dictyostelium centrosomes consist of a nucleus-associated cylindrical, three-layered core structure surrounded by a corona consisting of microtubule-nucleation complexes embedded in a scaffold of large coiled-coil proteins. One of them is the conserved CDK5RAP2 protein. Here we focus on the role of Dictyostelium CDK5RAP2 for maintenance of centrosome integrity, its interaction partners and its dynamic behavior during interphase and mitosis. GFP-CDK5RAP2 is present at the centrosome during the entire cell cycle except from a short period during prophase, correlating with the normal dissociation of the corona at this stage...
April 23, 2018: Cells
Rhys A Watkins, Alexandre Andrews, Charlotte Wynn, Caroline Barisch, Jason S King, Simon A Johnston
Cryptococcus neoformans is an environmental yeast that can cause opportunistic infections in humans. As infecting animals does not form part of its normal life-cycle, it has been proposed that the virulence traits that allow cryptococci to resist immune cells were selected through interactions with environmental phagocytes such as amoebae. Here, we investigate the interactions between C. neoformans and the social amoeba Dictyostelium discoideum . We show that like macrophages, D. discoideum is unable to kill C...
2018: Frontiers in Cellular and Infection Microbiology
Qudes Al-Anbaky, Zeiyad Al-Karakooly, Richard Connor, Lisa Williams, Azure Yarbrough, John Bush, Nawab Ali
Programed cell death or apoptosis is a key developmental process that maintains tissue homeostasis in multicellular organisms. Inositol polyphosphates (InsPs) are key signaling molecules known to regulate a variety of cellular processes including apoptosis in such organisms. The signaling role of InsPs in unicellular organisms such as Dictyostelium discoideum (D. discoideum) is not well understood. We investigated whether InsPs also play any role in apoptosis in D. discoideum and whether InsPs-mediated apoptosis follows a mechanism similar to that present in higher multicellular eukaryotes...
April 20, 2018: Molecular and Cellular Biochemistry
Ranjani Dhakshinamoorthy, Moritz Bitzhenner, Pierre Cosson, Thierry Soldati, Matthias Leippe
Due to their archaic life style and microbivor behavior, amoebae may represent a source of antimicrobial peptides and proteins. The amoebic protozoon Dictyostelium discoideum has been a model organism in cell biology for decades and has recently also been used for research on host-pathogen interactions and the evolution of innate immunity. In the genome of D. discoideum , genes can be identified that potentially allow the synthesis of a variety of antimicrobial proteins. However, at the protein level only very few antimicrobial proteins have been characterized that may interact directly with bacteria and help in fighting infection of D...
2018: Frontiers in Cellular and Infection Microbiology
Michael P Koonce, Irina Tikhonenko
The variability in centrosome size, shape, and activity among different organisms provides an opportunity to understand both conserved and specialized actions of this intriguing organelle. Centrosomes in the model organism Dictyostelium sp. share some features with fungal systems and some with vertebrate cell lines and thus provide a particularly useful context to study their dynamics. We discuss two aspects, centrosome positioning in cells and their interactions with nuclei during division as a means to highlight evolutionary modifications to machinery that provide the most basic of cellular services...
April 12, 2018: Cells
Kimberly Baumgardner, Connie Lin, Richard A Firtel, Jesus Lacal
The migration of cells according to a diffusible chemical signal in their environment is called chemotaxis, and the slime mold Dictyostelium discoideum is widely used for the study of eukaryotic chemotaxis. Dictyostelium must sense chemicals, such as cAMP, secreted during starvation to move toward the sources of the signal. Previous work demonstrated that the gskA gene encodes the Dictyostelium homologue of glycogen synthase kinase 3 (GSK3), a highly conserved serine/threonine kinase, which plays a major role in the regulation of Dictyostelium chemotaxis...
April 6, 2018: Environmental Microbiology
Mayumi Mori, Ravindra Mode, Jean Pieters
Microbes have interacted with eukaryotic cells for as long as they have been co-existing. While many of these interactions are beneficial for both the microbe as well as the eukaryotic cell, several microbes have evolved into pathogenic species. For some of these pathogens, host cell invasion results in irreparable damage and thus host cell destruction, whereas others use the host to avoid immune detection and elimination. One of the latter pathogens is Mycobacterium tuberculosis , arguably one of the most notorious pathogens on earth...
2018: Frontiers in Cellular and Infection Microbiology
Pauline Schaap, Christina Schilde
Not long ago, protists were considered one of four eukaryote kingdoms, but recent gene-based phylogenies show that they contribute to all nine eukaryote subdomains. The former kingdoms of animals, plants and fungi are now relegated to lower ranks within subdomains. Most unicellular protists respond to adverse conditions by differentiating into dormant walled cysts. As cysts, they survive long periods of starvation, drought and other environmental threats, only to re-emerge when conditions improve. For protists pathogens, the resilience of their cysts can prevent successful treatment or eradication of the disease...
April 5, 2018: Microbiology
Weiye Wang, Song Chen, Satarupa Das, Wolfgang Losert, Carole A Parent
Dictyostelium discoideum cells transport adenylyl cyclase A (ACA) containing vesicles to the back of polarized cells to relay exogenous cAMP signals during chemotaxis. Fluorescence in situ hybridization (FISH) experiments showed that ACA mRNA is also asymmetrically distributed at the back of polarized cells. Using the MS2 bacteriophage system, we now visualized the distribution of ACA mRNA in live chemotaxing cells. We found that the ACA mRNA localization is not dependent on the translation of the protein product and requires multiple cis-acting elements within the ACA coding sequence...
April 3, 2018: Journal of Cell Science
Byeonggyu Park, Hyeseon Kim, Taeck Joong Jeon
The small GTPase Ras proteins are involved in diverse cellular processes. We investigated the functions of RapC, one of 15 Ras subfamily GTPases in Dictyostelium. Loss of RapC resulted in a spread shape of cells; severe defects in cytokinesis leading to multinucleation; decrease of migration speed in chemoattractant-mediated cell migration, likely through increased cell adhesion; and aberrations in multicellular development producing abnormal multiple tips from one mound and multi-branched developmental structures...
March 31, 2018: Biochemical and Biophysical Research Communications
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