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dictyNews Volume 26 Number 17
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.
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Announcement
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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]
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Abstracts
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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]
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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]
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[End dictyNews, volume 26, number 17] 
