The Plasmodium Class XIV Myosin, MyoB, Has a Distinct Subcellular Location in Invasive and Motile Stages of the Malaria Parasite and an Unusual Light Chain

J Biol Chem. 2015 May 8;290(19):12147-64. doi: 10.1074/jbc.M115.637694. Epub 2015 Mar 23.


Myosin B (MyoB) is one of the two short class XIV myosins encoded in the Plasmodium genome. Class XIV myosins are characterized by a catalytic "head," a modified "neck," and the absence of a "tail" region. Myosin A (MyoA), the other class XIV myosin in Plasmodium, has been established as a component of the glideosome complex important in motility and cell invasion, but MyoB is not well characterized. We analyzed the properties of MyoB using three parasite species as follows: Plasmodium falciparum, Plasmodium berghei, and Plasmodium knowlesi. MyoB is expressed in all invasive stages (merozoites, ookinetes, and sporozoites) of the life cycle, and the protein is found in a discrete apical location in these polarized cells. In P. falciparum, MyoB is synthesized very late in schizogony/merogony, and its location in merozoites is distinct from, and anterior to, that of a range of known proteins present in the rhoptries, rhoptry neck or micronemes. Unlike MyoA, MyoB is not associated with glideosome complex proteins, including the MyoA light chain, myosin A tail domain-interacting protein (MTIP). A unique MyoB light chain (MLC-B) was identified that contains a calmodulin-like domain at the C terminus and an extended N-terminal region. MLC-B localizes to the same extreme apical pole in the cell as MyoB, and the two proteins form a complex. We propose that MLC-B is a MyoB-specific light chain, and for the short class XIV myosins that lack a tail region, the atypical myosin light chains may fulfill that role.

Keywords: Invasion; Malaria; Molecular Motor; Myosin; Myosin Light Chain; Parasite; Peptide Interaction; Plasmodium.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Calmodulin / chemistry
  • Circular Dichroism
  • Fluorescent Antibody Technique, Indirect
  • Green Fluorescent Proteins / chemistry
  • Molecular Sequence Data
  • Myosin Light Chains / chemistry
  • Nonmuscle Myosin Type IIA / chemistry
  • Nonmuscle Myosin Type IIB / chemistry*
  • Peptides / chemistry
  • Plasmodium berghei / metabolism*
  • Plasmodium falciparum / metabolism*
  • Plasmodium knowlesi / metabolism*
  • Protein Binding
  • Protein Denaturation
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Protozoan Proteins / chemistry*
  • Sequence Homology, Amino Acid


  • Calmodulin
  • Myosin Light Chains
  • Peptides
  • Protozoan Proteins
  • Green Fluorescent Proteins
  • Nonmuscle Myosin Type IIA
  • Nonmuscle Myosin Type IIB