Alternative Exon 9-Encoded Relay Domains Affect More than One Communication Pathway in the Drosophila Myosin Head

Bloemink, Marieke J. and Dambacher, Corey M. and Knowles, Aileen F. and Melkani, Girish C. and Geeves, Michael A. and Bernstein, Sanford I. (2009) Alternative Exon 9-Encoded Relay Domains Affect More than One Communication Pathway in the Drosophila Myosin Head. Journal of Molecular Biology, 389 (4). pp. 707-721. ISSN 0022-2836. (doi:https://doi.org/10.1016/j.jmb.2009.04.036) (Full text available)

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http://dx.doi.org/10.1016/j.jmb.2009.04.036

Abstract

We investigated the biochemical and biophysical properties of one of the four alternative regions within the Drosophila myosin catalytic domain: the relay domain encoded by exon 9. This domain of the myosin head transmits conformational changes in the nucleotide-binding pocket to the converter domain, which is crucial to coupling catalytic activity with mechanical movement of the lever arm. To study the function of this region, we used chimeric myosins (IFI-9b and EMB-9a), which were generated by exchange of the exon 9-encoded domains between the native embryonic body wall (EMB) and indirect flight muscle isoforms (IFI). Kinetic measurements show that exchange of the exon 9-encoded region alters the kinetic properties of the myosin S1 head. This is reflected in reduced values for ATP-induced actomyosin dissociation rate constant (K(1)k(+2)) and ADP affinity (K(AD)), measured for the chimeric constructs IFI-9b and EMB-9a, compared to wild-type IFI and EMB values. Homology models indicate that, in addition to affecting the communication pathway between the nucleotide-binding pocket and the converter domain, exchange of the relay domains between IFI and EMB affects the communication pathway between the nucleotide-binding pocket and the actin-binding site in the lower 50-kDa domain (loop 2). These results suggest an important role of the relay domain in the regulation of actomyosin cross-bridge kinetics.

Item Type: Article
Subjects: Q Science
Divisions: Faculties > Sciences > School of Biosciences
Depositing User: Sue Davies
Date Deposited: 26 Apr 2012 14:58 UTC
Last Modified: 20 May 2014 15:41 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/29363 (The current URI for this page, for reference purposes)
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