dictyNews
Electronic Edition
Volume 48, number 25
December 9, 2022
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Abstracts
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Sequential action of antibacterial effectors in Dictyostelium
discoideum phagosomes
Crespo-Yanez X, Oddy J, Lamrabet O, Jauslin T, Marchetti A,
Cosson P.
Mol Microbiol. 2022;10.1111/mmi.15004.
Mammalian professional phagocytic cells ingest and kill invading
microorganisms and prevent the development of bacterial infections.
Our understanding of the sequence of events that results in bacterial
killing and permeabilization in phagosomes is still largely incomplete.
In this study, we used the Dictyostelium discoideum amoeba as a
model phagocyte to study the fate of the bacteria Klebsiella
pneumoniae inside phagosomes. Our analysis distinguishes three
consecutive phases: bacteria first lose their ability to divide (killing),
then their cytosolic content is altered (permeabilization), and finally
their DNA is degraded (digestion). Phagosomal acidification and
production of free radicals are necessary for rapid killing, membrane-
permeabilizing proteins BpiC and AlyL are required for efficient
permeabilization. These results illustrate how a combination of
genetic and microscopical tools can be used to finely dissect the
molecular events leading to bacterial killing and permeabilization in
a maturing phagosome.
Submitted by Otmane Lamrabet [[log in to unmask]]
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Yellow polyketide pigment suppresses premature hatching in social
amoeba
Markus Günther, Christin Reimer, Rosa Herbst, Johann E Kufs, Julia
Rautschek, Nico Ueberschaar, Shuaibing Zhang , Gundela Peschel,
Lisa Reimer, Lars Regestein, Vito Valiante, Falk Hillmann,
Pierre Stallforth
PNAS, in press
Low-molecular-weight natural products from microbes are
indispensable in the development of potent drugs. However, their
biological roles within an ecological context often remain elusive. Here,
we shed light on natural products from eukaryotic microorganisms that
have the ability to transition from single cells to multicellular organisms:
the social amoebae. These eukaryotes harbor a large number of
polyketide biosynthetic genes in their genomes, yet virtually none of the
corresponding products can be isolated or characterized. Using
complementary molecular biology approaches, including CRISPR-Cas9,
we generated polyketide synthase (pks5) inactivation and overproduction
strains of the social amoeba Dictyostelium discoideum. Differential,
untargeted metabolomics of wild-type versus mutant fruiting bodies
allowed us to pinpoint candidate metabolites derived from the amoebal
PKS5. Extrachromosomal expression of the respective gene led to the
identification of a yellow polyunsaturated fatty acid. Analysis of the
temporospatial production pattern of this compound in conjunction with
detailed bioactivity studies revealed the polyketide to be a spore
germination suppressor.
Submitted by Markus Günther [[log in to unmask]]
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[End dictyNews, volume 48, number 25]
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