Monomeric myosin V uses two binding regions for the assembly of stable translocation complexes

Proc Natl Acad Sci U S A. 2007 Dec 11;104(50):19778-83. doi: 10.1073/pnas.0706780104. Epub 2007 Dec 4.

Abstract

Myosin-motors are conserved from yeast to human and transport a great variety of cargoes. Most plus-end directed myosins, which constitute the vast majority of all myosin motors, form stable dimers and interact constitutively with their cargo complexes. To date, little is known about regulatory mechanisms for cargo-complex assembly. In this study, we show that the type V myosin Myo4p binds to its cargo via two distinct binding regions, the C-terminal tail and a coiled-coil domain-containing fragment. Furthermore, we find that Myo4p is strictly monomeric at physiologic concentrations. Because type V myosins are thought to require dimerization for processive movement, a mechanism must be in place to ensure that oligomeric Myo4p is incorporated into cargo-translocation complexes. Indeed, we find that artificial dimerization of the Myo4p C-terminal tail promotes stabilization of myosin-cargo complexes, suggesting that full-length Myo4p dimerizes in the cocomplex as well. We also combined the Myo4p C-terminal tail with the coiled-coil region, lever arm, and motor domain from a different myosin to form constitutively dimeric motor proteins. This heterologous motor successfully translocates its cargo in vivo, suggesting that wild-type Myo4p may also function as a dimer during cargo-complex transport.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dimerization
  • Myosin Heavy Chains / genetics
  • Myosin Heavy Chains / metabolism
  • Myosin Type V / chemistry
  • Myosin Type V / genetics
  • Myosin Type V / metabolism*
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Transport
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism

Substances

  • MYO3 protein, S cerevisiae
  • Myo4 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Myosin Type V
  • Myosin Heavy Chains