Consequences of inducing intrinsic disorder in a high-affinity protein-protein interaction.

Papadakos, Grigorios and Sharma, Amit and Lancaster, Lorna E. and Bowen, Rebecca and Kaminska, Renata and Leech, Andrew P. and Walker, Daniel and Redfield, Christina and Kleanthous, Colin (2015) Consequences of inducing intrinsic disorder in a high-affinity protein-protein interaction. ACS Publications, 137 (16). 5252–5255. (https://doi.org/10.1021/ja512607r)

[thumbnail of Papadakos-etal-AP2015-Consequences-inducing-intrinsic-disorder-high-affinity-protein-protein-interaction]
Preview
Text. Filename: Papadakos_etal_AP2015_Consequences_inducing_intrinsic_disorder_high_affinity_protein_protein_interaction.pdf
Final Published Version
License: Creative Commons Attribution 4.0 logo

Download (956kB)| Preview

Abstract

The kinetic and thermodynamic consequences of intrinsic disorder in protein–protein recognition are controversial. We address this by inducing one partner of the high-affinity colicin E3 rRNase domain–Im3 complex (Kd ≈ 10–12 M) to become an intrinsically disordered protein (IDP). Through a variety of biophysical measurements, we show that a single alanine mutation at Tyr507 within the hydrophobic core of the isolated colicin E3 rRNase domain causes the enzyme to become an IDP (E3 rRNaseIDP). E3 rRNaseIDP binds stoichiometrically to Im3 and forms a structure that is essentially identical to the wild-type complex. However, binding of E3 rRNaseIDP to Im3 is 4 orders of magnitude weaker than that of the folded rRNase, with thermodynamic parameters reflecting the disorder-to-order transition on forming the complex. Critically, pre-steady-state kinetic analysis of the E3 rRNaseIDP–Im3 complex demonstrates that the decrease in affinity is mostly accounted for by a drop in the electrostatically steered association rate. Our study shows that, notwithstanding the advantages intrinsic disorder brings to biological systems, this can come at severe kinetic and thermodynamic cost.