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dictyNews Volume 26 Number 09
dictyNews
Electronic Edition
Volume 26, number 9
March 17, 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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Abstracts
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DNA Damage Signaling and Repair in Dictyostelium discoideum
Duen-Wei Hsu1, Pascale Gaudet2, Jessica J. R. Hudson1, Catherine J. Pears1
and Nicholas D. Lakin1
1Department of Biochemistry; University of Oxford; Oxford, UK
2dictyBase; Northwestern University; Chicago, Illinois USA
Cell Cycle, in press
Repair of DNA double strand breaks (DSBs) is critical for the maintenance of
genome integrity. DNA DSBs can be repaired by either homologous recombination
(HR) or nonhomologous end-joining (NHEJ). Whilst HR requires sequences
homologous to the damaged DNA template in order to facilitate repair, NHEJ
occurs through recognition of DNA DSBs by a variety of proteins that process
and rejoin DNA termini by direct ligation. Here we review two recent reports
that NHEJ is conserved in the social amoeba Dictyostelium discoideum.
Certain components of the mammalian NHEJ pathway that are absent in
genetically tractable organisms such as yeast are present in Dictyostelium
and we discuss potential directions for future research, in addition to
considering this organism as a genetic model system for the study of NHEJ in
vivo.
Submitted by: Nick Lakin [nicholas.lakin@bioch.ox.ac.uk]
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Goldberg, J.M., E.S. Wolpin, L. Bosgraaf, B. Clarkson, P.J.M. Van Haastert,
and J.L. Smith. (2006) Myosin light chain kinase A is activated by
cGMP-dependent and cGMP-independent pathways.
FEBS Lett., in press.
Stimulation of Dictyostelium cells with the chemoattractant cAMP results in
transient phosphorylation of the myosin regulatory light chain (RLC). We
show that myosin light chain kinase A (MLCK-A) is responsible for RLC
phosphorylation during chemotaxis, and that MLCK-A itself is transiently
phosphorylated on threonine-166, dramatically increasing its catalytic
activity. MLCK-A activation during chemotaxis is highly responsive to
cellular cGMP levels and the cGMP-binding protein GbpC. MLCK-A- cells have
a partial cytokinesis defect, and do not phosphorylate RLC in response to
concanavalin A (conA), but cells lacking cGMP or GbpC divide normally and
phosphorylate in response to conA. Thus MLCK-A is activated by a
cGMP/GbpC-independent mechanism activated during cytokinesis or by conA,
and a cGMP/GbpC-dependent pathway during chemotaxis.
Submitted by: Janet Smith [janet.l.smith@gmail.com]
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[End dictyNews, volume 26, number 9] 
