Linking Ras to myosin function: RasGEF Q, a Dictyostelium exchange factor for RasB, affects myosin II functions

Mondal, Subhanjan; Bakthavatsalam, Deenadayalan; Steimle, Paul; Gassen, Berthold; Rivero, Francisco; Noegel, Angelika A.

Abstract

Ras guanine nucleotide exchange factor (GEF) Q, a nucleotide exchange factor from Dictyostelium discoideum, is a 143-kD protein containing RasGEF domains and a DEP domain. We show that RasGEF Q can bind to F-actin, has the potential to form complexes with myosin heavy chain kinase (MHCK) A that contain active RasB, and is the predominant exchange factor for RasB. Overexpression of the RasGEF Q GEF domain activates RasB, causes enhanced recruitment of MHCK A to the cortex, and leads to cytokinesis defects in suspension, phenocopying cells expressing constitutively active RasB, and myosin-null mutants. RasGEF Q(-) mutants have defects in cell sorting and slug migration during later stages of development, in addition to cell polarity defects. Furthermore, RasGEF Q(-) mutants have increased levels of unphosphorylated myosin II, resulting in myosin II overassembly. Collectively, our results suggest that starvation signals through RasGEF Q to activate RasB, which then regulates processes requiring myosin II.

Citation

Mondal, S., Bakthavatsalam, D., Steimle, P., Gassen, B., Rivero, F., & Noegel, A. A. (2008). Linking Ras to myosin function: RasGEF Q, a Dictyostelium exchange factor for RasB, affects myosin II functions. Journal of Cell Biology, 181(5), 747-760. https://doi.org/10.1083/jcb.200710111

• Journal Article Type: Article
• Acceptance Date: May 1, 2008
• Online Publication Date: May 26, 2008
• Publication Date: Jun 2, 2008
• Deposit Date: Nov 13, 2014
• Publicly Available Date: Nov 13, 2014
• Journal: Journal of cell biology
• Print ISSN: 0021-9525
• Publisher: Rockefeller University Press
• Peer Reviewed: Peer Reviewed
• Volume: 181
• Issue: 5
• Pages: 747-760
• DOI: https://doi.org/10.1083/jcb.200710111
• Keywords: Actins; Animals; Chemotaxis; Cyclic AMP; Cytokinesis; Dictyostelium; Genetic techniques; Guanine nucleotide exchange factors; Light; Models; Biological; Myosin type II; Myosins; Phosphorylation; Protein binding; Protein structure; Tertiary; Proteins; Reco
• Public URL: https://hull-repository.worktribe.com/output/465016
• Publisher URL: http://jcb.rupress.org/content/181/5/747
• Additional Information: Copy of article first published in Journal of cell biology, 2008, v.181, issue 5
• Contract Date: Nov 13, 2014