dictyNews Electronic Edition Volume 35, number 2 July 10, 2010 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 ========= Redundant and unique roles of coronin proteins in Dictyostelium Maria C. Shina, Annette Müller-Taubenberger, Can Ünal, Michael Schleicher, Michael Steinert, Ludwig Eichinger, Rolf Müller, Rosemarie Blau-Wasser, Gernot Glöckner, Angelika A. Noegel Cellular and Molecular Life Sciences, in press Dictyostelium discoideum harbors a short (CRN12) and a long coronin (CRN7) composed of one and two beta-propellers, respectively. They are primarily present in the cell cortex and cells lacking CRN12 (corA-) or CRN7 (corB-) have defects in actin driven processes. We compared the characteristics of a mutant cell line (corA-/corB-) lacking CRN12 and CRN7 with the single mutants focusing on cytokinesis, phagocytosis, chemotaxis and development. Cytokinesis, uptake of small particles, and developmental defects were not enhanced in the corA-/corB- strain as compared to the single mutants, whereas motility and phagocytosis of yeast particles were more severely impaired. It appears that although both proteins affect the same processes they do not act in a redundant manner. Rather, they often act antagonistically which is in accordance with their proposed roles in the actin cytoskeleton where CRN12 acts in actin disassembly whereas CRN7 stabilizes actin filaments and protects them from disassembly. Submitted by Angelika Nögel [noegel@uni-koeln.de] -------------------------------------------------------------------------------- Synthesis and biological activity of peptides equivalent to the IP22 repeat motif found in proteins from Dictyostelium and Mimivirus Andrew Catalano a, Wei Luo b, Yali Wang b, and Danton H. O’Day a,b,* aDepartment of Cell and Systems Biology, University of Toronto, 25 Harbord st., Toronto, Ontario, Canada, M5S 3G5 bDepartment of Biology, University of Toronto at Mississauga, 3359 Mississauga rd. N., Mississauga, Ontario, Canada, L5L 1C6 Peptides, in press A novel IP22 repeat motif of unknown function was discovered previously that comprises almost the entire structure of cmbB, a calmodulin-binding protein from Dictyostelium discoideum. An analysis of over 2000 IP22 repeats across 130 different proteins from different species allowed us to define a prototypical IP22 repeat: I/LPxxhxxhxhxxxhxxxhxxxx (where L = leucine, I = isoleucine, h = any hydrophobic amino acid, x = any amino acid). Here we describe the synthesis of three peptide variants of the IP22 motif: IP22-1(IPNSVTSLKFGDGFNQPLTPGT; 22aa); IP22-2 (LPSTLKTISLSNSTDKKIFKNS; 22aa); and, IP22-3 (IPKSLRSLFLGKGYNQPLEF; 20aa) plus a control peptide from the N-term of cmbB (HNMNPFSPQLDEKKNSHIVEY; 21aa). The structure and purity of synthesized peptides were verified by HPLC and mass spectrometry. The peptides all dose-dependently enhanced random cell motility and cAMP-mediated chemotaxis in Dictyostelium but IP22-3 was most effective peaking in activity around 50μM. Fluorescein isothiocyanate (FITC) -conjugated IP22 peptides did not penetrate cells suggesting these peptides affect cell motility via cell surface interactions. Treatment of cells with FITC-IP22 peptides also led to enhanced cell motility equivalent to the non-conjugated peptides. Treatment of IP22-3-stimulated cells with 50μM LY294002, 20μM quinacrine or both suggests that IP22-3 requires both phosphoinositol 3-kinase and phospholipase A2 signaling to elicit its effects, a mechanism unique from EGFL motility-enhancing peptides. The mechanism of action and potential uses of IP22 repeat peptides are discussed. Submitted by Danton O'Day [danton.oday@utoronto.ca] ============================================================== [End dictyNews, volume 35, number 2]