Molecular mechanisms of parasite motility

Check out our latest myosin work!

Isa's work on Plasmodium falciparum myosin B is out on the preprint server bioRxiv - just in time for her PhD defense. Hopefully soon in peer-reviewed form too.

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Inari Kursula

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In this paper, we describe the expression and purification of the smallest of the malaria parasite myosins, MyoB, in complex with the calmodulin-like domain of its known light chain MLC-B. We characterized the complex using small-angle X-ray scattering, circular dichroism spectroscopy, and biochemical assays to determine the kinetics of the MyoB ATPase cycle. The complex has an overall shape of a monomeric myosin motor domain. The MyoB neck region can bind to several other regulatory light chains, in addition to MLC-B. However, we could not identify any essential light chain that would bind to the first IQ domain of the MyoB neck - either in the presence or absence of MLC-B. The recombinant MyoB moved actin filaments in vitro, and its ADP release rate was faster than the ATP turnover. MyoB has a much higher affinity to actin than the other small class XIV myosin of the parasite, MyoA. This supports a role in tethering and/or force sensing during early stages of invasion, where MyoB is strictly localized to the apical end of the parasite.

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