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.


=============
  Abstracts
=============



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] 

-----------------------------------------------------------------------------


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]
==============================================================================
[End dictyNews, volume 26, number 9]