Dicty News Electronic Edition Volume 24, number 4 February 25, 2005 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 Dicty-News, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. ============= Abstracts ============= Microbial Development Fisher, P.R. Encyclopedia of Molecular Cell Biology and Medicine, in press. Development is not only restricted to large multicellular animals and plants but is also a feature of the life cycles of microorganisms. The environment of a microorganism is rapidly changeable so that both eukaryotic and prokaryotic microbes have evolved developmental strategies to enhance their nutrient-scavenging abilities or in more extreme circumstances to form dormant, resistant cells (spores). The spores can survive under harsh conditions that do not support growth and can be dispersed to other environments that do. The endospores of pathogenic Clostridium species are amongst the most resistant cells on earth, and their destruction (or removal) is the key criterion for successful microbiological sterilization. Developmental programs in microbial pathogens are initiated in response to infection of the host and play important roles in pathogenesis. However, the best-understood examples of microbial development are not pathogens, but free-living microbes. The general principles underlying microbial development are being elucidated by their study. Submitted by: Paul R. Fisher [P.Fisher@latrobe.edu.au] ----------------------------------------------------------------------------- Identification and characterization of a novel alpha kinase with a vWFA motif localized to the contractile vacuole and Golgi complex in Dictyostelium discoideum Venkaiah Betapudi, Cynthia Mason, Lucila Licate and Thomas T. Egelhoff Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4970, USA. Mol. Biol. Cell in Press We have identified a novel unconventional protein kinase in Dictyostelium discoideum which carries the same conserved class of "alpha kinase" catalytic domain as previously reported in myosin heavy chain kinases (MHCKs) in this amoeba, but which has a completely novel domain organization. This protein of 625 amino acids contains an N-terminal von Willebrand Factor A (vWFA) motif (also known as beta-integrin motif), and is therefore named as VwkA. Manipulation of VwkA expression level via high copy number plasmids (VwkA++ cells) or gene disruption (vwkA null cells) results in an array of cellular defects, including impaired growth and multinucleation in suspension culture, impaired development, and alterations in myosin II abundance and assembly level. Despite sequence similarity to MHCKs, the purified protein failed to phosphorylate myosin II in vitro. Autophosphorylation activity however, was enhanced by calcium/calmodulin, and the enzyme can be precipitated from cellular lysates with calmodulin-agarose, suggesting that VwkA may directly bind calmodulin. VwkA is cytosolic in distribution, but enriched on the membranes of the contractile vacuole and Golgi-like structures in the cell. We propose that VwkA likely acts indirectly to influence myosin II abundance and assembly behavior, and possibly has broader roles the previously characterized alpha kinases in this organism which all appear to be MHC kinases. Submitted by: Dr. Tom Egelhoff [tte@po.cwru.edu] ----------------------------------------------------------------------------- GOAT: an R tool for analyzing Gene Ontology term enrichment Qikai Xu and Gad Shaulsky Graduate Program in Structural and Computational Biology and Molecular Biophysics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX Applied Bioinformatics, in press Summary: Understanding the composition of gene lists that result from high throughput experiments requires elaborate processing of gene annotation lists. Here we present GOAT, a tool based on the statistical software "R" for analyzing Gene Ontology (GO) term enrichment in gene lists. Given a gene list, GOAT calculates the enrichment and statistical significance of every GO term and generates graphical presentations of significantly enriched terms. GOAT works for any organism with a genome-scale GO annotation and allows easy updates of ontologies and annotations. Availability: GOAT is freely available (see supplement). Supplementary information: http://dictygenome.org/software/GOAT/ Key words: Gene Ontology (GO), GOAT, Microarray, R Submitted by: Gadi Shaulsky [gadi@bcm.tmc.edu] ----------------------------------------------------------------------------- A Dictyostelium homologue of WASP is required for polarized F-actin assembly during chemotaxis. Scott A. Myers, Ji W. Han, Yoonsung Lee, Richard A. Firtel, and Chang Y. Chung. Molecular Biology of the Cell The actin cytoskeleton controls the overall structure of cells and is highly polarized in chemotaxing cells, with F-actin assembled predominantly in the anterior leading edge and to a lesser degree in the cell's posterior. Wiscott-Aldrich syndrome protein (WASP) has emerged as a central player in controlling actin polymerization. We have investigated WASP function and its regulation in chemotaxing Dictyostelium cells and demonstrated the specific and essential role of WASP in organizing polarized F-actin assembly in chemotaxing cells. Cells expressing very low levels of WASP show reduced F-actin levels and significant defects in polarized F-actin assembly, resulting in an inability to establish axial polarity during chemotaxis. GFP-WASP preferentially localizes at the leading edge and uropod of chemotaxing cells and the B domain of WASP is required for the localization of WASP. We demonstrated that the B domain binds to PI(4,5)P2 and PI(3,4,5)P3 with similar affinities. The interaction between the B domain and PI(3,4,5)P3 plays an important role for the localization of WASP to the leading edge in chemotaxing cells. Our results suggest that the spatial and temporal control of WASP localization and activation is essential for the regulation of directional motility. Submitted by: Chang Chung [chang.chung@vanderbilt.edu] ============================================================================== [End Dicty News, volume 24, number 4]