Expression and characterization of a functional myosin head fragment in Dictyostelium discoideum

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Science  03 Nov 1989:
Vol. 246, Issue 4930, pp. 656-658
DOI: 10.1126/science.2530629


The isolated head fragment of myosin is a motor protein that is able to use energy liberated from the hydrolysis of adenosine triphosphate to cause sliding movement of actin filaments. Expression of a myosin fragment nearly equivalent to the amino-terminal globular head domain, generally referred to as subfragment 1, has been achieved by transforming the eukaryotic organism Dictyostelium discoideum with a plasmid that carries a 2.6-kilobase fragment of the cloned Dictyostelium myosin heavy chain gene under the control of the Dictyostelium actin-15 promoter. The recombinant fragment of the myosin heavy chain was purified 2400-fold from one of the resulting cell lines and was found to be functional by the following criteria: the myosin head fragment copurified with the essential and regulatory myosin light chains, decorated actin filaments, and displayed actin-activated adenosine triphosphatase activity. In addition, motility assays in vitro showed that the recombinant myosin fragment is capable of supporting sliding movement of actin filaments.

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