University of Oulu

Pires, Isa; Hung, Yu-Fu; Bergmann, Ulrich; Molloy, Justin E. and Kursula, Inari. “Analysis of Plasmodium Falciparum Myosin B ATPase Activity and Structure in Complex with the Calmodulin-like Domain of Its Light Chain MLC-B.” Journal of Biological Chemistry 298, no. 12 (December 2022): 102634.

Analysis of Plasmodium falciparum myosin B ATPase activity and structure in complex with the calmodulin-like domain of its light chain MLC-B

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Author: Pires, Isa1; Hung, Yu-Fu1; Bergmann, Ulrich1;
Organizations: 1Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
2Single Molecule Enzymology Laboratory, Francis Crick Institute, London, UK
3Department of Biomedicine, University of Bergen, Bergen, Norway
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: American Society for Biochemistry and Molecular Biology, 2022
Publish Date: 2023-06-12


Myosin B (MyoB) is a class 14 myosin expressed in all invasive stages of the malaria parasite, Plasmodium falciparum. It is not associated with the glideosome complex that drives motility and invasion of host cells. During red blood cell invasion, MyoB remains at the apical tip of the merozoite but is no longer observed once invasion is completed. MyoB is not essential for parasite survival, but when it is knocked out, merozoites are delayed in the initial stages of red blood cell invasion, giving rise to a growth defect that correlates with reduced invasion success. Therefore, further characterization is needed to understand how MyoB contributes to parasite invasion. Here, we have expressed and purified functional MyoB with the help of parasite-specific chaperones Hsp90 and Unc45, characterized its binding to actin and its known light chain MLC-B using biochemical and biophysical methods and determined its low-resolution structure in solution using small angle X-ray scattering. In addition to MLC-B, we found that four other putative regulatory light chains bind to the MyoB IQ2 motif in vitro. The purified recombinant MyoB adopted the overall shape of a myosin, exhibited actin-activated ATPase activity, and moved actin filaments in vitro. Additionally, we determined that the ADP release rate was faster than the ATP turnover number, and thus, does not appear to be rate limiting. This, together with the observed high affinity to actin and the specific localization of MyoB, may point toward a role in tethering and/or force sensing during early stages of invasion.

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Series: Journal of biological chemistry
ISSN: 0021-9258
ISSN-E: 1083-351X
ISSN-L: 0021-9258
Volume: 298
Issue: 12
Article number: 102634
DOI: 10.1016/j.jbc.2022.102634
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: This work was funded by the Academy of Finland (I. K.), Emil Aaltonen foundation (I. K.), Sigrid Jusélius foundation (I. K.), the Norwegian Research Council (I. K.) and Francis Crick Institute core funding (J. E. M.); Cancer Research UK (FC001119), UK Medical Research Council (FC001119), Wellcome Trust (FC001119).
Dataset Reference: All the relevant data and plasmids used to support the findings of this study are available upon request from the corresponding authors.
Copyright information: © 2022 THE AUTHORS. Published by Elsevier Inc on behalf of American Society for Biochemistry and Molecular Biology. This is an open access article under the CC BY license (