Toxoplasma gondii myosin A and its light chain: a fast, single-headed, plus-end-directed motor.
Successful host cell invasion is a prerequisite for survival of the obligate intracellular apicomplexan parasites and establishment of infection. Toxoplasma gondii penetrates host cells by an active process involving its own actomyosin system and which is distinct from induced phagocytosis. Toxoplasma gondii myosin A (TgMyoA) is presumed to achieve power gliding motion and host cell penetration by the capping of apically released adhesins towards the rear of the parasite. We report here an extensive biochemical characterization of the functional TgMyoA motor complex. TgMyoA is anchored at the plasma membrane and binds a novel type of myosin light chain (TgMLC1). Despite some unusual features, the kinetic and mechanical properties of TgMyoA are unexpectedly similar to those of fast skeletal muscle myosins. Microneedle-laser trap and sliding velocity assays established that TgMyoA moves in unitary steps of 5.3 nm with a velocity of 5.2 microm/s towards the plus end of actin filaments. TgMyoA is the first fast, single-headed myosin and fulfils all the requirements for power parasite gliding.
Herm-Götz
Angelika
A
Zentrum für Molekulare Biologie, Universität Heidelberg, Im Neuenheimer Feld 282, Germany.
Weiss
Stefan
S
Stratmann
Rolf
R
Fujita-Becker
Setsuko
S
Ruff
Christine
C
Meyhöfer
Edgar
E
Soldati
Thierry
T
Manstein
Dietmar J
DJ
Geeves
Michael A
MA
Soldati
Dominique
D
D000595:Amino Acid Sequence; D000818:Animals; D007700:Kinetics; D020409:Molecular Motor Proteins; D008969:Molecular Sequence Data; D018994:Myosin Light Chains / Q000502:physiology*; D024507:Nonmuscle Myosin Type IIA / Q000502:physiology*; D016415:Sequence Alignment; D014122:Toxoplasma / Q000502:physiology*
D020409:Molecular Motor Proteins; D018994:Myosin Light Chains; D024507:Nonmuscle Myosin Type IIA