Miranda Cargo-Binding Domain Forms an Elongated Coiled-Coil Homodimer in Solution: Implications for Asymmetric Cell Division in Drosophila

Protein Sci. 2008 May;17(5):908-17. doi: 10.1110/ps.083431408. Epub 2008 Mar 27.

Abstract

Miranda is a multidomain adaptor protein involved in neuroblast asymmetric division in Drosophila melanogaster. The central domain of Miranda is necessary for cargo binding of the neural transcription factor Prospero, the Prospero-mRNA carrier Staufen, and the tumor suppressor Brat. Here, we report the first solution structure of Miranda central "cargo-binding" domain (residues 460-660) using small-angle X-ray scattering. Ab initio modeling of the scattering data yields an elongated "rod-like" molecule with a maximum linear dimension (D(max)) of approximately 22 nm. Moreover, circular dichroism and cross-linking experiments indicate that the cargo-binding domain is predominantly helical and forms a parallel coiled-coil homodimer in solution. Based on the results, we modeled the full-length Miranda protein as a double-headed, double-tailed homodimer with a long central coiled-coil region. We discuss the cargo-binding capacity of the central domain and propose a structure-based mechanism for cargo release and timely degradation of Miranda in developing neuroblasts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Cycle Proteins / chemistry*
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Division
  • Dimerization
  • Drosophila Proteins / chemistry*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / cytology
  • Drosophila melanogaster / growth & development
  • Drosophila melanogaster / metabolism*
  • Models, Molecular*
  • Molecular Sequence Data
  • Protein Structure, Secondary / genetics
  • Protein Structure, Tertiary / genetics
  • Scattering, Small Angle
  • Solutions
  • Structure-Activity Relationship
  • X-Ray Diffraction

Substances

  • Cell Cycle Proteins
  • Drosophila Proteins
  • Mira protein, Drosophila
  • Solutions