In vitro reconstitution of an mRNA-transport complex reveals mechanisms of assembly and motor activation

J Cell Biol. 2013 Dec 23;203(6):971-84. doi: 10.1083/jcb.201302095.


The assembly and composition of ribonucleic acid (RNA)-transporting particles for asymmetric messenger RNA (mRNA) localization is not well understood. During mitosis of budding yeast, the Swi5p-dependent HO expression (SHE) complex transports a set of mRNAs into the daughter cell. We recombinantly reconstituted the core SHE complex and assessed its properties. The cytoplasmic precomplex contains only one motor and is unable to support continuous transport. However, a defined interaction with a second, RNA-bound precomplex after its nuclear export dimerizes the motor and activates processive RNA transport. The run length observed in vitro is compatible with long-distance transport in vivo. Surprisingly, SHE complexes that either contain or lack RNA cargo show similar motility properties, demonstrating that the RNA-binding protein and not its cargo activates motility. We further show that SHE complexes have a defined size but multimerize into variable particles upon binding of RNAs with multiple localization elements. Based on these findings, we provide an estimate of number, size, and composition of such multimeric SHE particles in the cell.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins
  • Cytoskeletal Proteins / metabolism
  • Cytoskeletal Proteins / physiology
  • Dimerization
  • Myosin Heavy Chains / metabolism
  • Myosin Heavy Chains / physiology
  • Myosin Type V / metabolism
  • Myosin Type V / physiology
  • RNA Transport / physiology*
  • RNA, Messenger / metabolism*
  • RNA-Binding Proteins / metabolism
  • RNA-Binding Proteins / physiology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / metabolism
  • Saccharomyces cerevisiae Proteins / physiology
  • Transcription Factors


  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • Myo4 protein, S cerevisiae
  • RNA, Messenger
  • RNA-Binding Proteins
  • SHE2 protein, S cerevisiae
  • SHE4 protein, S cerevisiae
  • SWI5 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Myosin Type V
  • Myosin Heavy Chains