Macropinocytosis is a fundamental mechanism that allows cells to take up extracellular liquid into large vesicles. It critically depends on the formation of ring protrusive actin beneath plasma membrane, which develops macropinocytic cup. We show cups in Dictyostelium are organised around coincident intense patches PIP3, active Ras and Rac. These signalling invariably associated with SCAR/WAVE at their periphery, as all examined structures based PIP3 patches, including phagocytic basal...

The heterotetrameric AP and F-COPI complexes help to define the cellular map of modern eukaryotes. To search for related machinery, we developed a structure-based bioinformatics tool, identified core subunits TSET, 'missing link' between APs COPI. Studies in Dictyostelium indicate that TSET is heterohexamer, with two associated scaffolding proteins. non-essential Dictyostelium, but may act plasma membrane turnover, essentially identical recently described TPLATE complex, TPC. However,...

Cells use phagocytosis and macropinocytosis to internalise bulk material, which in phagotrophic organisms supplies the nutrients necessary for growth. Wildtype Dictyostelium amoebae feed on bacteria, but decades laboratory work has relied axenic mutants that can also grow liquid media. We used forward genetics identify causative gene underlying this phenotype. This encodes RasGAP Neurofibromin (NF1). Loss of NF1 enables growth by increasing fluid uptake. Mutants form outsized macropinosomes...

Sex Triangle The model organism Dictyostelium discoideum is a social amoeba that has three sexes, or mating types, do not resemble those in any other eukaryote studied so far. Any two sexes can form diploid zygote, which will recruit haploid cells to macrocyst. Bloomfield et al. (p. 1533 ; see the Perspective by Kessin ) found sex this determined several genes at locus on chromosome 5, with each type represented different version of locus. Not all were directly essential for successful...

Duplications of stretches the genome are an important source individual genetic variation, but their unrecognized presence in laboratory organisms would be a confounding variable for analysis. We report here that duplications 15 kb or more common social amoeba Dictyostelium discoideum. Most stocks axenic 'workhorse' strains Ax2 and Ax3/4 obtained from different laboratories can expected to carry duplications. The auxotrophic DH1 JH10 also bear previously unreported Strain is known large...

Reactive oxygen species are known to have a signalling role in many organisms. In bacteria and yeast various response systems evolved combat oxidative stress which triggered by reactive species. Mammals plants actively generate such as superoxide during responses variety of extracellular factors. We report here the generation molecule early development Dictyostelium discoideum. grows single amoebae but, on starvation, cells aggregate form multicellular organism. Superoxide is generated...

Abstract Background Phagocytosis plays a major role in the defense of higher organisms against microbial infection and provides also basis for antigen processing immune response. Cells model organism Dictyostelium are professional phagocytes that exploit phagocytosis bacteria as preferred way to ingest food, besides killing pathogens. We have investigated differential gene expression during non-pathogenic bacteria, using DNA microarrays, order identify molecular functions novel genes...

Fertilization is a central event in sexual reproduction, and understanding its molecular mechanisms has both basic applicative biological importance. Recent studies have uncovered the molecules that mediate this process variety of organisms, making it intriguing to consider conservation evolution reproduction across phyla. The social amoeba Dictyostelium discoideum undergoes maturation forms gametes under dark humid conditions. It exhibits three mating types, type-I, -II, -III, for...

Pseudomonas aeruginosa is one of the most relevant human opportunistic bacterial pathogens. Two strains (PAO1 and PA14) have been mainly used as models for studying virulence P. aeruginosa. The strain PA14 more virulent than PAO1 in a wide range hosts including insects, nematodes plants. Whereas some differences might be attributable to concerted action determinants encoded pathogenicity islands present genome PA14, global analysis differential host responses these has not addressed. Little...

Structures of social amoeba mating-type proteins suggest deep conservation sexual differentiation processes.

Sex promotes the recombination and reassortment of genetic material is prevalent across eukaryotes, although our knowledge molecular details sexual inheritance scant in several major lineages. In social amoebae, sex involves a promiscuous mixing cytoplasm before zygotes consume majority cells, but for technical reasons, progeny have been difficult to obtain study. We report here genome-wide characterization meiotic Dictyostelium discoideum . find that occurs at high frequency pairwise...

The mature fruiting body of Dictyostelium consists stalk and spore cells but its construction, the migration preceding slug stage, requires a number specialized sub-types prestalk cell whose nature function are not well understood. prototypic prestalk-specific gene, ecmA, is inducible by polyketide DIF-1 in monolayer assay DimB MybE transcription factors for full inducibility. We perform genome-wide microarray analyses, on parental, mybE- dimB- cells, identify many additional genes that...

ABSTRACT GskA, the Dictyostelium GSK-3 orthologue, is modified and activated by dual-specificity tyrosine kinase Zak1, two kinases form part of a signaling pathway that responds to extracellular cyclic AMP. We identify potential cellular effectors for analyzing corresponding null mutants. There are proteins mRNAs altered in abundance only one or other mutants, indicating each has some unique functions. However, proteomic microarray analyses identified number genes, respectively, similarly...

Background The retinoblastoma tumour suppressor, Rb, has two major functions. First, it represses genes whose products are required for S-phase entry and progression thus stabilizing cells in G1. Second, Rb interacts with factors that induce cell-cycle exit terminal differentiation. Dictyostelium lacks a G1 phase its cell cycle but orthologue, rblA. Methodology/Principal Findings Using microarray analysis mRNA-Seq transcriptional profiling, we show RblA strongly involved S mitosis. Both...

The Serum Response Factor (SRF) is an important regulator of cell proliferation and differentiation. Dictyostelium discoideum srfB gene codes for SRF homologue expressed in vegetative cells during development under the control three alternative promoters, which show different cell-type specific patterns expression. two more proximal promoters directed transcription prestalk AB, stalk lower-cup cells. generation a strain where has been interrupted (srfB(-)) shown that this required regulation...

In Dictyostelium, the cytoskeletal proteins Actin binding protein 1 (Abp1) and class I myosin MyoK directly interact couple actin dynamics to membrane deformation during phagocytosis. Together with kinase PakB, they build a regulatory switch that controls efficiency of uptake large particles. As basis for further functional dissection, exhaustive phagosome proteomics was performed established about 1300 participate in biogenesis. Then, quantitative comparative proteomic analysis maturation...

There are 13 Dictyostelium Src homology 2 (SH2) domain proteins, almost 10-fold fewer than in mammals, and only three functionally unassigned. One of these, LrrB, contains a novel combination protein interaction domains: an SH2 leucine-rich repeat domain. Growth early development appear normal the mutant, but expression profiling reveals that genes active at these stages greatly underexpressed: ttdA metallohydrolase, abcG10 small molecule transporter, cinB esterase. In contrast, multigene...