MyoE

MyoE (PF3D7_0613900) is one of two Plasmodium Class XIV myosins that operates within the actomyosin motor machinery of invasive parasite stages, expressed across all invasive stages and localised to the basal end of the parasite (PMID:31283102). Gene deletion in P. berghei establishes that MyoE is functionally required for sporozoite traversal (PMID:31283102). Consistent with a role in the invasion motor, MyoE physically associates with the glideosome/inner-membrane-complex (IMC) network: endogenously tagged MyoE co-immunoprecipitates with CDPK4 and recovers glideosome and IMC components including GAP40 in P. berghei schizonts (PMID:30315162). Beyond this localisation, complex membership, and traversal phenotype, the enzymatic and motor mechanism of MyoE itself has not been characterized in the available corpus.

1. 2005 Low

   Establishing when MyoE is deployed narrowed its likely functional window: the question was whether MyoE acts in early replicating blood stages or in the invasive schizont/merozoite, and stage-resolved transcript profiling placed its expression at the schizont stage.

   Evidence RT-PCR of blood-stage parasite mRNA across developmental stages in P. falciparum

   PMID:15754360

   Open questions at the time

   • Transcript-only data; no protein-level expression or timing confirmed for MyoE in this study
   • Single method, single lab
   • Does not address function or localisation
2. 2018 Medium

   It was unknown whether MyoE physically integrates into the invasion motor; reciprocal co-immunoprecipitation placed MyoE within the glideosome/IMC protein network, linking it to CDPK4 and GAP40.

   Evidence Endogenous 3xHA tagging and cross-linked co-immunoprecipitation followed by mass spectrometry in P. berghei ANKA schizonts

   PMID:30315162

   Open questions at the time

   • Co-IP demonstrates association, not direct binding or the interface involved
   • Functional consequence of the CDPK4/GAP40 associations for MyoE activity untested
   • Interactions defined in schizonts; relevance to other invasive stages not shown
3. 2019 Medium

   Whether MyoE has a non-redundant biological role was open given the presence of a second Class XIV myosin (MyoB); gene deletion assigned MyoE a specific, non-redundant requirement in sporozoite traversal and defined its basal localisation.

   Evidence Gene deletion, immunofluorescence/live-imaging, and sporozoite traversal assay in P. berghei (expression also assessed in P. falciparum)

   PMID:31283102

   Open questions at the time

   • Molecular mechanism connecting basal localisation to the traversal defect not resolved
   • Whether the traversal role depends on the CDPK4/GAP40 associations untested
   • No biochemical demonstration of motor/ATPase activity

• The enzymatic and mechanochemical basis of MyoE function — its actin engagement, motor activity, and how basal localisation drives sporozoite traversal — remains unresolved.
• No reconstitution or ATPase/motility assay for MyoE
• No structural model of MyoE or its complex
• Mechanism of basal recruitment unknown