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WD-Repeat domains target Dictyostelium myosin heavy chain kinase activities by binding directly to myosin II

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Paul A. Steimle, Assistant Professor (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: Myosin heavy chain kinase (MHCK) A phosphorylates mapped sites at the C-terminal tail of Dictyostelium myosin II heavy chain, driving disassembly of myosin filaments both in vitro and in vivo. MHCK A is organized into three functional domains that include an N-terminal coiled-coil region, a central kinase catalytic domain unrelated to conventional protein kinases, and a WD repeat domain at the C terminus. MHCK B is a homologue of MHCK A that possesses structurally related catalytic and WD repeat domains. In the current study, we explored the role of the WD repeat domains in defining the activities of both MHCK A and MHCK B using recombinant bacterially expressed truncations of these kinases either with or without their WD repeat domains. We demonstrate that substrate targeting is a conserved function of the WD repeat domains of both MHCK A and MHCK B and that this targeting is specific forDictyostelium myosin II filaments. We also show that the mechanism of targeting involves direct binding of the WD repeat domains to the myosin substrate. To our knowledge, this is the first report of WD repeat domains physically targeting attached kinase domains to their substrates. The examples presented here may serve as a paradigm for enzyme targeting in other systems.

Additional Information

Publication
Journal of Biological Chemistry. 276:6853-6860
Language: English
Date: 2000
Keywords
Myosin heavy chain kinase, Dictyostelium myosin, N-terminal coiled-coil region, Complex cellular processes