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dictyNews Volume 17 Number 05
Dicty News
Electronic Edition
Volume 17, number 5
Sept. 8, 2001
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.
=====================================================
NEW JOURNAL - "Eukaryotic Cell" - CALL FOR PAPERS
=====================================================
The American Society for Microbiology is pleased to announce publication
of an important new journal focusing on eukaryotic microbiology,
Eukaryotic Cell. This bimonthly publication, commencing publication in
February 2002 in both print and online formats, will present reports of
basic research on simple eukaryotic microorganisms such as yeasts, fungi,
algae, protozoa, and social amoebae. Topics will include, but are not
limited to: basic biology; molecular and cellular biology; mechanisms,
and control, of developmental pathways; structure and form inherent in
basic biological processes; cellular architecture; metabolic physiology;
comparative genomics, biochemistry, and evolution; population dynamics;
and ecology. In addition, the journal will consider manuscripts dealing
with the viruses of these organisms and their organelles and with
interactions with other living systems, where the focus is clearly on the
eukaryotic cell.
The board of editors of Eukaryotic Cell is led by Editor in Chief C. C.
Wang and includes Jay C. Dunlap, Ursula W. Goodenough, Ching Kung, Adam
Kuspa, and Aaron P. Mitchell.
Manuscripts should be sent to where they will be forwarded to the
appropriate editor:
Journals Department,
American Society for Microbiology
1752 N St., N.W.,
Washington, DC 20036-2904, USA.
Format, policies and procedures should follow those given in the
Instructions to Authors for the other ASM journals.
These Instructions and sample articles may be
accessed at: http://www.journals.asm.org/misc/eukaryot.shtml
=====================
PostDoc Positions
=====================
A Microarray Resource for the Dictyostelium Research Community
Based in Cambridge, UK
Funding has recently been awarded by the Wellcome Trust to generate
microarrays for the protozoan organism Dictyostelium discoideum, which
is widely used to study such basic biological questions as chemotaxis,
signal transduction and development. This project, a collaboration
between the Sanger Centre (Drs. Bart Barrell and Al Ivens
[barrell@sanger.ac.uk; alicat@sanger.ac.uk]) and the MRC Laboratory
of Molecular Biology (LMB) (Dr. Rob Kay [rrk@mrc-lmb.cam.ac.uk]),
will utilise all available genome sequence data to produce a publicly
available, biologically characterised resource.
Two three-year postdoctoral positions are available from 1st
November 2001. One position will be based at, and employed by, the
Sanger Centre. This position will be expected to play the major role
in bioinformatics aspects of the project. The second individual, based
at, and employed by, the LMB, will specialise predominantly in
Dictyostelium biology (MRC Band 4).
Both positions would be expected to work on all aspects of the
project, including developing a suitable strategy with the PIs for
producing this resource and for initiating and maintaining
collaborations to ask biologically interesting questions using the arrays.
The starting salaries for both positions will be based upon
qualifications and experience.
For further information, please refer to:
http://www.sanger.ac.uk/Projects/D_discoideum/Arrays/
http://www.mrc-lmb.cam.ac.uk/research/CB/Kay_R/Kay_R.html
http://dictybase.org/dicty.html
To apply for either position, please write with your CV and current
salary details to: The Personnel Officer, The Sanger Centre, Wellcome
Trust Genome Campus, Hinxton, Cambridge CB10 1SA.
Closing date: 28 September 2001.
All candidates will be contacted after: 8 October 2001.
==============
Abstracts
==============
Dynamics of the Dictyostelium Arp2/3 Complex in Endocytosis, Cytokinesis,
and Chemotaxis
Robert Insall*, Annette Mueller-Taubenberger+, Laura Machesky*, Jana
Koehler+, Evelyn Simmeth+, Simon J. Atkinson, Igor Weber+ and Guenther
Gerisch+
* School of Biosciences, Birmingham University, Birmingham B15 2TT, UK;
+ Max-Planck-Institut fuer Biochemie, D-82152 Martinsried, Germany;
Indiana University School of Medicine, Department of Medicine, 1120 South
Drive, FH-115, Indianapolis, IN 46202-5116.
Cell Motil. Cytoskeleton, accepted.
Abstract:
The Arp2/3 complex is a ubiquitous and important regulator of the actin
cytoskeleton. Here we identify this complex from Dictyostelium and
investigate its dynamics in live cells. The predicted sequences of the
subunits show a strong homology to the members of the mammalian complex,
with the larger subunits generally better conserved than the smaller ones.
In the highly motile cells of Dictyostelium the Arp2/3 complex is rapidly
re-distributed to the cytoskeleton in response to external stimuli. Fusions
of Arp3 and p41-Arc with GFP reveal that in phagocytosis, macropinocytosis
and chemotaxis the complex is recruited within seconds to sites where actin
polymerization is induced. In contrast, there is little or no localization
to the cleavage furrow during cytokinesis. Rather the Arp2/3 complex is
enriched in ruffles at the polar regions of mitotic cells, which suggests
a role in actin polymerization in these ruffles.
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Coactosin-like Protein, a human F-actin binding protein: Critical role of
lysine-75
Patrick Provost*, Johanne Doucet*, Alexander Stock+, Guenther Gerisch+,
Bengt Samuelsson* and Olof Radmark*
* Department of Medical Biochemistry and Biophysics, Division of Physiological
Chemistry II, Karolinska Institute, S-17177 Stockholm, Sweden;
+ Max-Planck-Institut fuer Biochemie, D-82152 Martinsried, Germany.
Biochem. J., accepted.
This paper is not strictly a Dicty paper, but deals with the human homologue
of coactosin, an actin binding protein first described in Dictyostelium
(DeHostos et al., Cell Motil. Cytoskeleton 26, 181-191 (1993)). Another
paper on this human coactosin-like protein (CLP) has appeared in J. Biol.
Chem. 276, 16520-16527 (2001): Provost, P., J. Doucet, T. Hammarberg, G.
Gerisch, B. Samuelsson and O. Radmark: 5-Lipoxygenase Interacts with
Coactosin-like Protein.
Abstract:
Coactosin-like Protein (CLP) was recently identified in a yeast two-hybrid
screen using 5-lipoxygenase as a bait. Here, we report the functional
characterization of CLP as a human filamentous actin (F-actin) binding protein.
CLP mRNA shows a wide tissue distribution and is predominantly expressed in
placenta, lung, kidney and peripheral blood leukocytes. Endogenous CLP protein
is localized in the cytosol of myeloid cells. Using a two-hybrid approach,
actin was identified as a CLP-interacting protein. Binding experiments
indicated that CLP associates with F-actin but does not form a stable
complex with G-actin. In transfected mammalian cells, CLP colocalized with
actin stress fibers. CLP bound to actin filaments in a stoichiometry of 1:2
actin subunits, but could be cross-linked to only one subunit of actin.
Site-directed mutagenesis revealed the involvement of Lys-75 of CLP in
actin binding, a residue highly conserved in related proteins and supposed
to be exposed on the surface of the CLP protein. Our results identify CLP as
a new human protein that binds F-actin in vitro and in vivo, and indicate
that Lys-75 is essential for this interaction.
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Characterization of CD36/LIMPII-homologues in Dictyostelium discoideum
Klaus-Peter Janssen, Ren Rost, Ludwig Eichinger, and Michael Schleicher
A.-Butenandt-Institut fr Zellbiologie, Ludwig-Maximilians-Universitaet,
80336 Muenchen, FRG.
accepted: J. Biol. Chem.
The CD36/LIMPII family is ubiquitously expressed in higher eukaryotes and
comprises integral membrane proteins that have in part been characterized
as cell adhesion receptors, scavenger receptors, or fatty acids transporters.
However, no physiological role has been defined so far for the members of
this family that localize specifically to vesicular compartments rather than
to the cell surface, namely LIMPII (lysosomal integral membrane protein type
II) from mammals and LmpA from the amoeba Dictyostelium discoideum. LmpA, the
first described CD36/LIMPII homologue from lower eukaryotes, has initially
been identified as a suppressor of the profilin-minus phenotype. Here we report
the discovery and initial characterization of two new CD36/LIMPII-related
proteins, which both share several features with LmpA: (I) their size is
considerably larger than that of the CD36/LIMPII proteins from higher
eukaryotes, (II) they show the characteristic hairpin-topology of this protein
family, (III) they are heavily N-glycosylated, (IV) they localize to vesicular
structures of endo-lysosomal origin. However, they show intriguing differences
in their developmental regulation and exhibit different sorting signals of the
di-leucine or tyrosine-type in their carboxyterminal tail domains. These
features make them promising candidates as paradigm for the study of the
function and evolution of the yet poorly understood CD36/LIMPII proteins.
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[End Dicty News, volume 17, number 5]
