Investigation into Early Steps of Actin Recognition by the Intrinsically Disordered N-WASP Domain V.

Maud Chan-Yao-Chong,Tâp Ha-Duong,Dominique Durand

doi:10.3390/ijms20184493

Abstract

Cellular regulation or signaling processes are mediated by many proteins which often have one or several intrinsically disordered regions (IDRs). These IDRs generally serve as binders to different proteins with high specificity. In many cases, IDRs undergo a disorder-to-order transition upon binding, following a mechanism between two possible pathways, the induced fit or the conformational selection. Since these mechanisms contribute differently to the kinetics of IDR associations, it is important to investigate them in order to gain insight into the physical factors that determine the biomolecular recognition process. The verprolin homology domain (V) of the Neural Wiskott–Aldrich Syndrome Protein (N-WASP), involved in the regulation of actin polymerization, is a typical example of IDR. It is composed of two WH2 motifs, each being able to bind one actin molecule. In this study, we investigated the early steps of the recognition process of actin by the WH2 motifs of N-WASP domain V. Using docking calculations and molecular dynamics simulations, our study shows that actin is first recognized by the N-WASP domain V regions which have the highest propensity to form transient -helices. The WH2 motif consensus sequences “LKKV” subsequently bind to actin through large conformational changes of the disordered domain V.

Highlights

Disordered proteins (IDPs) play important roles in the regulation of many biological processes, such as cell growth, cell signaling, and cell survival
Closer investigations are required to gain insight into the early events and pathways of the Intrinsically disordered proteins (IDPs)–protein recognition mechanism. We address these issues in the case of the verprolin homology domain (V) of the Neural Wiskott–Aldrich Syndrome Protein (N-WASP), which has two WASP-homology 2 (WH2) motifs
NMR experiments and molecular dynamics (MD) simulations previously showed that unbound N-WASP domain V has two transient α-helical structures at regions 10–15 and 37–43 corresponding to residues 407–412 and 434–440 in the whole protein sequence (Figure S1) [29]

Summary

Introduction

Disordered proteins (IDPs) play important roles in the regulation of many biological processes, such as cell growth, cell signaling, and cell survival. WH2 motifs are intrinsically disordered, and, in complex with actin, they all share a similar binding mode: their N-terminal part folds into an α-helix which interacts with the barbed face of actin, between subdomains 1 and 3, while their central consensus sequence “LKKV” has an extended conformation which lies on the actin’s surface, between subdomains 1 and 2 [11,14,15] (see Figure 2B). These actin–WH2 motif structures were determined by X-ray diffraction, the common folding of different WH2 motifs upon binding to actin indicates, with reasonable confidence, that it is probably similar to the one adopted in solution

Methods

Results

Conclusion