dictyNews Electronic Edition Volume 26, number 17 June 02, 2006 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. ============== Announcement ============== Katz, E.R.: Kenneth Raper, Elisha Mitchell and Dictyostelium, J. Biosci.31: June 2006 At last years Dicty meeting I presented a paper on the early history of Dictyostelium. It specifically tried to answer the question of why Ken Raper chose to publish his monumental 1940 paper in the Journal of the Elisha Mitchell Scientific Society. A number of people asked me to write it up, and, with the help of Vidya Nanjundiah I have now done so. http://www.ias.ac.in/jbiosci/jun2006/contents.htm Gene Katz [ekatz@notes.cc.sunysb.edu] ============= Abstracts ============= Isolation, characterization and bioinformatic analysis of calmodulin binding protein cmbB reveals a novel tandem IP22 repeat common to many Dictyostelium and Mimivirus proteins Danton H. O'Day1,4, Karsten Suhre2, Michael A. Myre3, Munmun Chatterjee-Chakraborty1, and Sara E. Chavez1 1Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario L5L 1C6 CANADA 2Structural and Genomic Information Laboratory, CNRS UPR2589, Institute for Structural Biology and Microbiology (IBSM), Parc Scientifique de Luminy, 163 Avenue de Luminy, 13288 Marseille Cedex 09 FRANCE 3MassGeneral Institute for Neurodegenerative Disease, Harvard Medical School, Massachusetts General Hospital, 114 16th Street, Rm. 3801, Charlestown MA 02129-9142 USA Biochemical Biophysical Research Communications, in press A novel calmodulin binding protein cmbB from Dictyostelium discoideum is encoded in a single gene. Northern analysis reveals two cmbB transcripts first detectable at 4h during multicellular development. Western blotting detects an ~46.6 kDa protein. Sequence analysis and calmodulin-agarose binding studies identified a 'classic' calcium-dependent calmodulin binding domain (179IPKSLRSLFLGKGYNQPLEF198) but structural analyses suggest binding may not involve classic alpha-helical calmodulin-binding. The cmbB protein is comprised of tandem repeats of a newly identified IP22 motif ([I,L]Pxxhxxhxhxxxhxxxhxxxx; where h = any hydrophobic amino acid) that is highly conserved and a more precise representation of the FNIP repeat. At least eight Acanthamoeba polyphaga Mimivirus proteins and over 100 Dictyostelium proteins contain tandem arrays of the IP22 motif and its variants. cmbB also shares structural homology to YopM, from the plague bacterium Yersenia pestis. Submitted by: Danton H. O'Day [doday@utm.utoronto.ca] ----------------------------------------------------------------------------- Trishanku, a novel regulator of cell-type stability and morphogenesis in Dictyostelium discoideum. Jyoti Kumar Jaiswal(1,2,*), Nameeta Mujumdar(1), Harry K. MacWilliams(3) and Vidyanand Nanjundiah(1) (1)Indian Institute of Science, Bangalore, (2)The Rockefeller University, New York, and (3)Ludwig-Maximilians-Universitaet, Muenchen. Differentiation, in press By random insertional mutagenesis of Dictyostelium discoideum we have identified a novel gene, trishanku (triA), which codes for a BTB domain-containing novel protein. TriA is expressed strongly during the late G2 phase of cell cycle and in presumptive spore (prespore) cells. Disruption of triA reduces aggregate size, destabilizes cell fate, results in fruiting bodies with thicker stalk and spore mass that remains sub-terminal. The spore to stalk ratio is lower than wild type; the spores are small and spherical. These changes can be reversed by expressing the triA gene under a constitutive or a prespore-specific promoter. Chimeras formed with the wild type cells show that TriA acts in a cell-autonomous fashion. Aggregating triA- cells exhibit a delayed appearance of EDTA resistant cell-cell adhesion, which may cause the stream break in triA- aggregates and in chimeric aggregates formed with wild type cells. Using stable and labile beta galactosidase reporters we show that in triA- slugs the prestalk/prespore proportion is normal, but there is increased transdifferentiation between the two cell types. The ÔstalkyÕ nature of the fruiting body appears to be due to the tendency of all cells with current or past prestalk gene expression to contribute to the stalk. Finally the spore mass in triA- culminants is sub-terminal because midway through culmination it detaches from upper cup cells. In chimeras with wild type, the wild type spore mass rises to the top of the stalk, but the triA- spore mass remains sub-terminal. Thus, prespore cells play an active role in their rise along the stalk, contrary to what has been suggested. Defects in the adhesion-related properties of prespore cells and their accelerated maturation are possible explanations that require further investigation. Submitted by: Jyoti Jaiswal [jaiswaj@mail.rockefeller.edu] ============================================================================== [End dictyNews, volume 26, number 17]