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Altering the stability of the Cdc8 overlap region modulates the ability of this tropomyosin to bind cooperatively to actin and regulate myosin.

East, Daniel A., Sousa, Duncan, Martin, Stephen R., Edwards, Thomas A., Lehman, William, Mulvihill, Daniel P. (2011) Altering the stability of the Cdc8 overlap region modulates the ability of this tropomyosin to bind cooperatively to actin and regulate myosin. Biochemical Journal, 438 (2). pp. 265-273. ISSN 0264-6021. (doi:10.1042/BJ20101316) (KAR id:28037)

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Tropomyosin (Tm) is an evolutionarily conserved ?-helical coiled-coil protein, dimers of which form end-to-end polymers capable of associating with and stabilising actin-filaments and regulate myosin function. The fission yeast, Schizosaccharomyces pombe, possesses a single essential Tm, Cdc8, which can be acetylated on its amino terminal methionine to increase its affinity for actin and enhance its ability to regulate myosin function. We have designed and generated a number of novel Cdc8 mutant proteins with amino terminal substitutions to explore how stability of the Cdc8-polymer overlap region affects the regulatory function of this Tm. By correlating the stability of each protein, its propensity to form stable polymers, its ability to associate with actin and to regulate myosin, we have shown the stability of the amino terminal of the Cdc8 ?-helix is crucial for Tm function. In addition we have identified a novel Cdc8 mutant with increased amino-terminal stability, dimers of which are capable of forming Tm-polymers significantly longer than the wild-type protein. This protein had a reduced affinity for actin with respect to wild type, and was unable to regulate actomyosin interactions. The data presented here are consistent with acetylation providing a mechanism for modulating the formation and stability of Cdc8 polymers within the fission yeast cell. The data also provide evidence for a mechanism in which Tm dimers form end-to-end polymers on the actin-filament, consistent with a cooperative model for Tm binding to actin.

Item Type: Article
DOI/Identification number: 10.1042/BJ20101316
Subjects: Q Science
Q Science > QH Natural history > QH301 Biology
Q Science > QP Physiology (Living systems) > QP506 Molecular biology
Q Science > QP Physiology (Living systems) > QP517 Biochemistry
Divisions: Divisions > Division of Natural Sciences > Biosciences
Funders: European Commission (
Biotechnology and Biological Sciences Research Council (
National Institutes of Health (
Depositing User: Daniel Mulvihill
Date Deposited: 29 Jul 2011 09:33 UTC
Last Modified: 12 Jul 2022 10:40 UTC
Resource URI: (The current URI for this page, for reference purposes)
Mulvihill, Daniel P.:
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