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Miranda cargo-binding domain forms an elongated coiled-coil homodimer in solution: implications for asymmetric cell

Mohammad S Yousef1, Hironari Kamikubo, Mikio Kataoka

  • 1Structural Biology Research Center, Photon Factory, IMSS, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan. yousef@post.kek.jp

Protein Science : a Publication of the Protein Society
|March 29, 2008
PubMed

Insights

The central domain of Miranda protein forms a rod-like homodimer, crucial for binding neural proteins during asymmetric cell division in Drosophila neuroblasts.

Area of Science:

  • Developmental Biology
  • Molecular Biology
  • Structural Biology

Background:

  • Miranda is a key adaptor protein regulating asymmetric neuroblast division in Drosophila.
  • Its central domain binds essential neural factors like Prospero, Staufen, and Brat.

Purpose of the Study:

  • To determine the solution structure of the Miranda central cargo-binding domain.
  • To elucidate the structural basis of Miranda's cargo-binding function and dimerization.

Main Methods:

  • Small-angle X-ray scattering (SAXS) for solution structure determination.
  • Ab initio modeling based on SAXS data.
  • Circular dichroism (CD) and cross-linking experiments.

Main Results:

  • The Miranda central domain (residues 460-660) is an elongated, rod-like molecule (~22 nm).
  • It exists as a parallel coiled-coil homodimer in solution, predominantly helical.
  • A model of full-length Miranda suggests a dimeric structure with a central coiled-coil.

Conclusions:

  • The dimeric structure of the central domain is essential for its cargo-binding capacity.
  • Proposes a structure-based mechanism for cargo release and Miranda degradation in neuroblasts.

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