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Structural characterization of the MIT domain from human Vps4b

Hirotoshi Takasu1, Jun Goo Jee, Ayako Ohno

  • 1International Graduate School of Arts and Sciences, Yokohama City University, Yokohama, Kanagawa 230 0045, Japan.

Biochemical and Biophysical Research Communications
|July 16, 2005
PubMed

Insights

The microtubule interacting and trafficking (MIT) domain

Area of Science:

  • Structural Biology
  • Cell Biology
  • Protein Science

Background:

  • The microtubule interacting and trafficking (MIT) domain is a conserved protein module with an undefined function.
  • MIT domains are found in proteins involved in diverse cellular processes, including Vps4, SNX15, and spastin.
  • A specific substitution (Ile58-to-Met) in the human Vps4b MIT domain (hVps4b) has been reported.

Purpose of the Study:

  • To determine the solution structure of the isolated MIT domain from human Vps4b.
  • To investigate the structural and functional implications of the Ile58-to-Met substitution.
  • To elucidate the potential role of the MIT domain in protein-protein interactions and cellular trafficking.

Main Methods:

  • Solution structure determination of the hVps4b MIT domain using biophysical techniques.
  • Sequence comparison analysis of MIT domains to identify conserved residues.
  • Thermal stability assays to assess the impact of the I58M substitution.

Main Results:

  • The hVps4b MIT domain adopts an 'up-and-down' three-helix bundle structure.
  • Conserved residues are critical for inter-helical contacts within the MIT domain.
  • The Ile58-to-Met substitution significantly decreases the thermal stability of the MIT domain.
  • A potential protein-binding crevice was identified on the MIT domain surface.

Conclusions:

  • The MIT domain's structure suggests a conserved structural framework.
  • The identified crevice may indicate a role as a protein-binding module.
  • The MIT domain is proposed as a putative adaptor for the ESCRT-III complex in endosomal trafficking.

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