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dictyNews Volume 38 Number 11
dictyNews
Electronic Edition
Volume 38, number 11
April 20, 2012
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.
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Abstracts
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The isoform B of the Dictyostelium long-chain fatty-acyl-coenzyme A
synthetase is initially inserted into the ER and subsequently provides
peroxisomes with an activity important for efficient phagocytosis.
Peggy Paschke, Nadine Pawolleck, Frauke Haenel, Heike Otto,
Harald Rhling, and Markus Maniak
Abteilung Zellbiologie, Universitt Kassel, 34109 Kassel, Germany
Eur. J. Cell Biol. in press
Long-chain fatty-acyl-coenzymeA synthetases activate fatty acids for
anabolic or catabolic metabolism. They often localize to more than one
organelle within eukaryotic cells. Dictyostelium contains two of these
proteins, FcsA and FcsB with the latter being targeted to the membrane
of the endoplasmic reticulum by virtue of an N-terminal signal sequence
and from there appears to move on to peroxisomes. Deletion of this
signal favours the peripheral association of the protein with the
mitochondrial surface instead. A strain lacking the activity of the FcsB
enzyme was constructed by homologous recombination. It has a severe
deficiency in the phagocytic uptake of particles, which can be partially
alleviated by a peroxisomally targeted, soluble FcsA enzyme. It is,
however, not rescued by expressing FcsA in the cytoplasm or targeting
it to the ER, indicating that peroxisomal beta-oxidation is important for
phagocytosis. In a fcsA-/B- double mutant phagocytosis efficiency is
similar to fcsB- cells. However, unlike the single mutants, the fcsA-/B-
strain is delayed in morphogenesis, but forms viable spores, albeit
within a small fruiting body. This developmental defect is also seen in
other mutants affecting peroxisomal enzymes involved in §-oxidation
and the glyoxylate cycle.
Submitted by Markus Maniak [maniak@uni-kassel.de]
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A lamin in lower eukaryotes?
Petros Batsios, Tatjana Peter, Otto Baumann, Reimer Stick,
Irene Meyer, Ralph Grf
Dept. of Cell Biology, Institute for Biochemistry and Biology,
University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14469
Potsdam-Golm, Germany
Nucleus, in press
Lamins are the major components of the nuclear lamina and serve
not only as a mechanical support, but are also involved in chromatin
organization, epigenetic regulation, transcription, and mitotic events.
Despite these universal tasks, lamins have so far been found only in
metazoans. Yet, recently we have identified Dictyostelium NE81 as
the first lamin-like protein in a lower eukaryote. Based on the current
knowledge, we draw a model for nuclear envelope organization in
Dictyostelium in this Extra View and we review the experimental data
that justified this classification. Furthermore we provide unpublished
data underscoring the requirement of posttranslational CaaX-box
processing for proper protein localization at the nuclear envelope.
Sequence comparison of NE81 sequences from four Dictyostelia with
bona fide lamins illustrates the evolutional relationship between these
proteins. Under certain conditions these usually unicellular social
amoebae congregate to form a multicellular body. We propose that
the evolution of the lamin-like NE81 went along with the invention of
multicellularity.
Submitted by Ralph Grf [rgraef@uni-potsdam.de]
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[End dictyNews, volume 38, number 11]
