Phosphorylation of actin-related protein 2 (Arp2) is required for normal development and cAMP chemotaxis in dictyostelium

Choi, C.-H., Thomason, P.A., Zaki, M., Insall, R.H. and Barber, D.D.L. (2013) Phosphorylation of actin-related protein 2 (Arp2) is required for normal development and cAMP chemotaxis in dictyostelium. Journal of Biological Chemistry, 288(4), pp. 2464-2474. (doi: 10.1074/jbc.M112.435313)

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Phosphorylation of the actin-related protein 2 (Arp2) subunit of the Arp2/3 complex on evolutionarily conserved threonine and tyrosine residues was recently identified and shown to be necessary for nucleating activity of the Arp2/3 complex and membrane protrusion of Drosophila cells. Here we use the Dictyostelium diploid system to replace the essential Arp2 protein with mutants that cannot be phosphorylated at Thr-235/6 and Tyr-200. We found that aggregation of the resulting mutant cells after starvation was substantially slowed with delayed early developmental gene expression and that chemotaxis toward a cAMP gradient was defective with loss of polarity and attenuated F-actin assembly. Chemotaxis toward cAMP was also diminished with reduced cell speed and directionality and shorter pseudopod lifetime when Arp2 phosphorylation mutant cells were allowed to develop longer to a responsive state similar to that of wild-type cells. However, clathrin-mediated endocytosis and chemotaxis under agar to folate in vegetative cells were only subtly affected in Arp2 phosphorylation mutants. Thus, phosphorylation of threonine and tyrosine is important for a subset of the functions of the Arp2/3 complex, in particular an unexpected major role in regulating development.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Thomason, Dr Peter and Insall, Professor Robert and Zaki, Dr Mehreen
Authors: Choi, C.-H., Thomason, P.A., Zaki, M., Insall, R.H., and Barber, D.D.L.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
Journal Name:Journal of Biological Chemistry
Publisher:American Society for Biochemistry and Molecular Biology, Inc.
Published Online:05 December 2012

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