Intrinsically Disordered Region Modulates Ligand Binding in Glutaredoxin 1 from Trypanosoma Brucei

Abstract

Glutaredoxins are small proteins that share a common well-conserved thioredoxin-fold and participate in a wide variety of biological processes. Among them, class II Grx are redox-inactive proteins involved in iron−sulfur (Fe-S) metabolism. In the present work, we report different structural and dynamics aspects of 1CGrx1 from the pathogenic parasite Trypanosoma brucei that differentiate it from other orthologues by the presence of a parasite-specific unstructured N-terminal extension whose role has not been fully elucidated yet. Previous nuclear magnetic resonance (NMR) studies revealed significant differences with respect to the mutant lacking the disordered tail. Herein, we have performed atomistic molecular dynamics simulations that, complementary to NMR studies, confirm the intrinsically disordered nature of the N-terminal extension. Moreover, we confirm the main role of these residues in modulating the conformational dynamics of the glutathione-binding pocket. We observe that the N-terminal extension modifies the ligand cavity stiffening it by specific interactions that ultimately modulate its intrinsic flexibility, which may modify its role in the storage and/or transfer of preformed iron−sulfur clusters. These unique structural and dynamics aspects of Trypanosoma brucei 1CGrx1 differentiate it from other orthologues and could have functional relevance. In this way, our results encourage the study of other similar protein folding families with intrinsically disordered regions whose functional roles are still unrevealed and the screening of potential 1CGrx1 inhibitors as antitrypanosomal drug candidates.

Drugging the Undruggable Trypanosoma brucei Monothiol Glutaredoxin 1

“…As shown in Figure 2 , panels B and C, the most perturbed residues are Val92, Thr93, Ile95, Lys96, Val126, Val131, Val132, Glu138, Glu141, and Val155, which correspond to residues nearby the putative GSH binding pocket. Interestingly, the three residues of the IDR that are significantly perturbed (Ile54, Phe61, and Ala76) belong to regions of the disordered tail proposed to transiently interact with the pocket [ 15 ]. This experimental evidence indicates that the ligand binding is specific and nicely agrees with the computational approach, where the ligand was rationally designed into the GSH binding site.…”

“…We recently revealed the structure of the mature form of T.b. 1CGrx1 including its intrinsically disordered region (IDR), which modulates the accessibility to the binding pocket [ 13 , 14 , 15 ]. It should be also noted that complementation studies performed in Saccharomyces cerevisiae deprived of its mitochondrial Grx5 indicate that inserting T.b.…”

Tardigrade Secretory-Abundant Heat-Soluble Protein Varies Entrance Propensity Depending on the Amino-Acid Sequence

“…The cavity volume was evaluated with the final structures from the ten simulations for each system, using Analysis of NULL Area (ANA) software, , which has been applied to evaluate the cavity volume for several proteins. − The amino-acid residues employed for the cavity definition (marked in Table S1) were selected by the following procedure. Cavities were determined using ANA on the basis of the crystal structure of RvSAHS1 (PDB 5XN9; chain A; alternate locations identifier, A).…”