Systematic analysis of Plasmodium myosins reveals differential expression, localization and function in invasive and proliferative parasite stages

Abstract

should be considered joint senior authors. Running title: Localization and function of myosins in Plasmodium SummaryThe myosin superfamily comprises of actin-dependent eukaryotic molecular motors important in a variety of cellular functions. Although well studied in many systems, knowledge of their functions in Plasmodium, the causative agent of malaria, is restricted.Previously, six myosins were identified in this genus, including three Class XIV myosins found only in Apicomplexa and some Ciliates. The well characterised MyoA, is a class XIV myosin essential for gliding motility and invasion. Here, we characterize all other Plasmodium myosins throughout the parasite life cycle and show that they have very diverse patterns of expression and cellular location. MyoB and MyoE, the other two Class XIV myosins, are expressed in all invasive stages, with apical and basal locations, respectively. Gene deletion revealed that MyoE is involved in sporozoite motility, MyoF and MyoK are likely essential in the asexual blood stages, and MyoJ and MyoB are not essential. Both MyoB and its essential light chain (MCL-B) are localised at the apical end of ookinetes but expressed at completely different time points. This work provides a better understanding of the role of actomyosin motors in Apicomplexan parasites, particularly in the motile and invasive stages of Plasmodium during sexual and asexual development within the mosquito.

The Actomyosin Systems in Apicomplexa

“…Its endogenous tagging allowed its detection only in mature oocysts when sporozoites are formed. PbMyoJ localizes at the junction between the sporozoites and the residual bodies, consistent with a basal localization but remains associated with the oocyst body upon egress of the sporozoites (Wall et al 2019). So far, it remains enigmatic how these different components contribute to the segregation of the schizonts, but these studies pave the way to a better understanding of the contractile ring, and the constriction and cytokinesis processes in Apicomplexa.…”

“…All the myosin heavy chains have been localized in T. gondii tachyzoites (Fig. 14.3) and P. berghei blood stages and their essentiality evaluated by the generation of knockout, when possible (Wall et al 2019;Herm-Götz et al 2006;Andenmatten et al 2013;Frénal et al 2014Frénal et al , 2017b, or knockdown (Meissner et al 2002;Siden-Kiamos et al 2011;Jacot et al 2013;Graindorge et al 2016) cell lines. Out of the 11 myosin heavy chains expressed by the tachyzoite, only two, TgMyoF and TgMyoH, have been completely refractory to deletion and thus are considered indispensable for parasite survival.…”

“…In Plasmodium species that lack an ortholog of TgMyoC, MyoA is likely essential for all motile stages of the life cycle as is the case for the P. berghei ookinete (Siden-Kiamos et al 2011). Moreover, in P. berghei, out of the five other myosin heavy chains, PbMyoF and PbMyoK are likely essential for the blood stages since their deletion was unsuccessful (Wall et al 2019). However, PbMyoB, PbMyoE, and PbMyoJ were shown to be dispensable for these asexual stages while the class XIV PbMyoE appeared critical for motility of the mosquito salivary gland sporozoites (Wall et al 2019).…”

“…Interestingly, co-immunoprecipitation experiments performed on P. falciparum schizonts with PfCINCH identified several new proteins of the basal complex and pulled-down PfMyoJ suggesting that in malaria parasites, a basal actomyosin system is responsible for constriction of the schizont basal pole, but also cytokinesis prior egress (Rudlaff et al 2019). As in T. gondii, PbMyoJ was successfully deleted in P. berghei without noticeable impact on its life cycle (Wall et al 2019). Its endogenous tagging allowed its detection only in mature oocysts when sporozoites are formed.…”

“…The same phenotype is also observed in the intraerythrocytic stages of P. falciparum depleted in PfACT1 or in PfFRM2 confirming the conservation of the machinery in Apicomplexa (Das et al 2017;Stortz et al 2018). In addition, PbMyoF is also likely essential in P. berghei since the attempts to delete the gene have been unsuccessful so far (Wall et al 2019). The primary function of MyoF is likely to maintain the positioning of the centrosomes during cell division.…”