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The intrinsically disordered Tarp protein from chlamydia binds actin with a partially preformed helix.

  • James Tolchard
    ,
  • Samuel J. Walpole
    ,
  • Andrew J. Miles
    ,
  • Robin Maytum
    ,
  • Lawrence A. Eaglen
    ,
  • Ted Hackstadt
  • University of East Anglia
    ,
  • Birkbeck University of London
    ,
  • Rocky Mountain Laboratories
Research Output: Contribution to journal Article Peer-review

Open access

Abstract

Tarp (translocated actin recruiting phosphoprotein) is an effector protein common to all chlamydial species that functions to remodel the host-actin cytoskeleton during the initial stage of infection. In C. trachomatis, direct binding to actin monomers has been broadly mapped to a 100-residue region (726-825) which is predicted to be predominantly disordered, with the exception of a ~10-residue α-helical patch homologous to other WH2 actin-binding motifs. Biophysical investigations demonstrate that a Tarp726-825 construct behaves as a typical intrinsically disordered protein; within it, NMR relaxation measurements and chemical shift analysis identify the ten residue WH2-homologous region to exhibit partial α-helix formation. Isothermal titration calorimetry experiments on the same construct in the presence of monomeric G-actin show a well defined binding event with a 1:1 stoichiometry and Kd of 102 nM, whilst synchrotron radiation circular dichroism spectroscopy suggests the binding is concomitant with an increase in helical secondary structure. Furthermore, NMR experiments in the presence of G-actin indicate this interaction affects the proposed WH2-like α-helical region, supporting results from in silico docking calculations which suggest that, when folded, this α-helix binds within the actin hydrophobic cleft as seen for other actin-associated proteins.

Publication Information

Output type

Research Output: Contribution to journal Article Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 1960

Journal (Volume, Issue Number)

Scientific Reports (Volume 31, Issue 8)

Publication milestones

  • Published - 31/01/2018

Publication status

Published - 31/01/2018

External Publication IDs

  • handle.net: 10547/622842
  • Scopus: 85046053673

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