Dicty News Electronic Edition Volume 21, number 9 September 19, 2003 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu. Back issues of Dicty-News, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. ============================================ Special Note to the Dictyostelium community ============================================ An order sheet for the Special Dictyostelium Issue (including a CD with movies) of the Journal of Muscle Research and Cell Motility can be found in the 'News' section at http://dictybase.org. The price of 60 Euro is a special offer that I have negotiated with Kluwer for the Dictyostelium community. Dietmar Manstein ============= Abstracts ============= Identification and Characterization of Novel Calcium-binding Proteins of Dictyostelium and Their Spatial Expression Patterns during Development Haruyo Sakamoto, Keiko Nishio, Mariko Tomisako, Hidekazu Kuwayama, Yoshimasa Tanaka, Isao Suetake, Shouji Tajima, Satoshi Ogihara, Barrie Coukell, and Mineko Maeda Develop., Growth, Differ. (in press) Five putative Ca2+-binding proteins, CBP5, 6, 7, 8 and 9, having EF-hand motifs were found by searching the Dictyostelium cDNA database. 45Ca2+-overlay experiments revealed that four of them (excluding CBP9) are real Ca2+-binding proteins. Northern blot analysis revealed that the genes encoding CBP5, 6, 7 and 8 are all developmentally regulated. In situ hybridization analyses revealed that spatial expression of these genes was regulated in several different manners. CBP1, 2, 3, 5, 6 and 7 are expressed in prespore cells in the slug stage. Transcripts of the genes for CBP1 and 5 are enriched in prestalk subtype PstO cells. On the other hand, CBP4 is expressed predominantly in PstO cells. CBP8 is evenly expressed at a very low level throughout the whole slug. Such distinct spatial expression patterns suggest that the CBPs might be involved in morphogenesis and might have their own roles either in prespore or in prestalk cell differentiation of Dictyostelium. Submitted by: Mineko Maeda [mmaeda@bio.sci.osaka-u.ac.jp] ----------------------------------------------------------------------------- A structural model for actin-induced nucleotide release in myosin Thomas F. Reubold#, Susanne Eschenburg#, Andreas Becker#, , F.Jon Kull#,¤ & Dietmar J. Manstein#,¦ #Max-Planck Institut fŸr medizinische Forschung, Abteilung Biophysik, Jahnstr. 29, D-69120 Heidelberg, Germany, ¤Dartmouth College Department of Chemistry, 6128 Burke Laboratory, Hanover, NH 03755, USA, ¦Institut fŸr Biophysikalische Chemie, OE 4350, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30623 Hannover, Germany Nature Structural Biology, in press Myosins are molecular motor proteins that harness the chemical energy stored in ATP in order to produce directed force along actin filaments. The detailed mechanism of force production is dependent on synchronized action of the various structural and functional elements of the myosin motor domain, and remains poorly understood. Complex communications pathways link the catalytic nucleotide binding region, the structures responsible for force amplification, and the actin binding domain of myosin1. We have crystallized the motor domain of myosin II in a new conformation in which switch I and switch II, conserved loop structures involved in nucleotide binding, have moved away from the binding pocket, resulting in a nucleotide-free state. These movements are linked to a rearrangement of the actin binding domains, which illuminate a previously unobserved communication pathway between the nucleotide binding site and the actin binding region, explain the reciprocal relationship between actin and nucleotide affinity and suggest a new mechanism for product release in myosin family motors. Submitted by: Dietmar J. Manstein [manstein@bpc.mh-hannover.de] =============================================================================== [End Dicty News, volume 21, number 9]