Regulation of the Plasmodium motor complex: phosphorylation of Myosin A Tail Interacting Protein (MTIP) loosens its grip on MyoA.

Regulation of the Plasmodium motor complex: phosphorylation of Myosin A Tail Interacting Protein (MTIP) loosens its grip on MyoA.

J Biol Chem. 2012 Aug 29

Douse CH, Green JL, Salgado PS, Simpson PJ, Thomas JC, Langsley G, Holder AA, Tate EW, Cota E.

Imperial College London, United Kingdom;

Abstract

The interaction between the C-terminal tail of myosin A (MyoA) and its light chain, myosin A tail domain interacting protein (MTIP), is an essential feature of the conserved molecular machinery required for gliding motility and cell invasion by Apicomplexa parasites. Recent data indicate that MTIP Ser107 and/or Ser108 are targeted for intracellular phosphorylation. Using an optimised MyoA tail peptide to reconstitute the complex, we show that this region of MTIP is an interaction hotspot using X-ray crystallography and NMR, and S107E and S108E mutants were generated to mimic the effect of phosphorylation. NMR relaxation experiments and other biophysical measurements indicate that the S108E mutation serves to break the tight clamp around the MyoA tail, whilst S107E has a smaller but measurable impact. These data are consistent with physical interactions observed between recombinant MTIP and native MyoA from P. falciparum lysates. Taken together, these data support the notion that the conserved interactions between MTIP and MyoA may be specifically modulated by this post-translational modification.

Full Text