Identification of myosin XI receptors in Arabidopsis defines a distinct class of transport vesicles

Plant Cell. 2013 Aug;25(8):3022-38. doi: 10.1105/tpc.113.113704. Epub 2013 Aug 30.

Abstract

To characterize the mechanism through which myosin XI-K attaches to its principal endomembrane cargo, a yeast two-hybrid library of Arabidopsis thaliana cDNAs was screened using the myosin cargo binding domain as bait. This screen identified two previously uncharacterized transmembrane proteins (hereinafter myosin binding proteins or MyoB1/2) that share a myosin binding, conserved domain of unknown function 593 (DUF593). Additional screens revealed that MyoB1/2 also bind myosin XI-1, whereas myosin XI-I interacts with the distantly related MyoB7. The in vivo interactions of MyoB1/2 with myosin XI-K were confirmed by immunoprecipitation and colocalization analyses. In epidermal cells, the yellow fluorescent protein-tagged MyoB1/2 localize to vesicles that traffic in a myosin XI-dependent manner. Similar to myosin XI-K, MyoB1/2 accumulate in the tip-growing domain of elongating root hairs. Gene knockout analysis demonstrated that functional cooperation between myosin XI-K and MyoB proteins is required for proper plant development. Unexpectedly, the MyoB1-containing vesicles did not correspond to brefeldin A-sensitive Golgi and post-Golgi or prevacuolar compartments and did not colocalize with known exocytic or endosomal compartments. Phylogenomic analysis suggests that DUF593 emerged in primitive land plants and founded a multigene family that is conserved in all flowering plants. Collectively, these findings indicate that MyoB are membrane-anchored myosin receptors that define a distinct, plant-specific transport vesicle compartment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / metabolism*
  • Cell Compartmentation
  • Conserved Sequence
  • Flowers / physiology
  • Fluorescence Recovery After Photobleaching
  • Gene Silencing
  • Green Fluorescent Proteins / metabolism
  • Models, Biological
  • Myosins / chemistry
  • Myosins / metabolism*
  • Phenotype
  • Phylogeny
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Transport
  • Receptors, Cell Surface / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Subcellular Fractions / metabolism
  • Transport Vesicles / metabolism*

Substances

  • Arabidopsis Proteins
  • Receptors, Cell Surface
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • Myosins