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Disordered TPPP/p25 binds GTP and displays Mg2+-dependent GTPase activity

Agnes Zotter1, Andrea Bodor, Judit Oláh

  • 1Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, H-1113 Budapest, Hungary.

FEBS Letters
|February 15, 2011
PubMed

Insights

Tubulin Polymerization Promoting Protein/p25 (TPPP/p25), a disordered protein, binds GTP in its flexible region and exhibits Mg(2+)-dependent GTPase activity, suggesting roles in cell physiology.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Neuroscience

Background:

  • The disordered Tubulin Polymerization Promoting Protein/p25 (TPPP/p25) is vital for microtubule dynamics and oligodendrocyte differentiation.
  • Understanding TPPP/p25's interaction with GTP is crucial for elucidating its physiological functions.

Purpose of the Study:

  • To investigate the structural localization of GTP binding within TPPP/p25.
  • To characterize the GTPase activity of TPPP/p25 and its dependence on Mg(2+).

Main Methods:

  • Multinuclear NMR spectroscopy to determine protein structure.
  • Affinity chromatography, fluorescence spectroscopy, and circular dichroism to study GTP binding.
  • Enzyme assays to measure GTPase activity.

Main Results:

  • Disordered segments of TPPP/p25 are located at the N- and C-terminals, flanking a flexible region.
  • GTP binds to TPPP/p25 within the flexible region, without affecting the terminal segments.
  • TPPP/p25 exhibits Mg(2+)-dependent GTP hydrolysis, with activity comparable to small G proteins.

Conclusions:

  • TPPP/p25 possesses intrinsic GTPase activity, suggesting a regulatory role beyond microtubule stabilization.
  • The findings open new avenues for exploring TPPP/p25's involvement in diverse physiological processes.

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