Dissecting a novel allosteric mechanism of cruzain: A computer-aided approach

PLoS One. 2019 Jan 25;14(1):e0211227. doi: 10.1371/journal.pone.0211227. eCollection 2019.

Abstract

Trypanosoma cruzi is the causative agent of Chagas disease, a neglected infection affecting millions of people in tropical regions. There are several chemotherapeutic agents for the treatment of this disease, but most of them are highly toxic and generate resistance. Currently, the development of allosteric inhibitors constitutes a promising research field, since it can improve the accessibility to more selective and less toxic medicines. To date, the allosteric drugs prediction is a state-of-the-art topic in rational structure-based computational design. In this work, a simulation strategy was developed for computational discovery of allosteric inhibitors, and it was applied to cruzain, a promising target and the major cysteine protease of T. cruzi. Molecular dynamics simulations, binding free energy calculations and network-based modelling of residue interactions were combined to characterize and compare molecular distinctive features of the apo form and the cruzain-allosteric inhibitor complexes. By using geometry-based criteria on trajectory snapshots, we predicted two main allosteric sites suitable for drug targeting. The results suggest dissimilar mechanisms exerted by the same allosteric site when binding different potential allosteric inhibitors. Finally, we identified the residues involved in suboptimal paths linking the identified site and the orthosteric site. The present study constitutes the first approximation to the design of cruzain allosteric inhibitors and may serve for future pharmacological intervention. Here, no major effects on active site structure were observed due to compound binding (modification of distance and angles between catalytic residues), which indicates that allosteric regulation in cruzain might be mediated via alterations of its dynamical properties similarly to allosteric inhibition of human cathepsin K (HCatK). The current findings are particularly relevant for the design of allosteric modulators of papain-like cysteine proteases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation / drug effects
  • Catalytic Domain / drug effects
  • Cathepsin K / chemistry
  • Cathepsin K / drug effects
  • Computer-Aided Design
  • Cysteine Endopeptidases / chemistry*
  • Cysteine Endopeptidases / metabolism*
  • Cysteine Proteinase Inhibitors / chemistry*
  • Cysteine Proteinase Inhibitors / pharmacology
  • Humans
  • Models, Molecular
  • Molecular Dynamics Simulation
  • Protein Conformation
  • Protozoan Proteins / chemistry*
  • Protozoan Proteins / metabolism*
  • Structure-Activity Relationship
  • Trypanocidal Agents / chemistry
  • Trypanocidal Agents / pharmacology
  • Trypanosoma cruzi / drug effects
  • Trypanosoma cruzi / metabolism*

Substances

  • Cysteine Proteinase Inhibitors
  • Protozoan Proteins
  • Trypanocidal Agents
  • Cysteine Endopeptidases
  • CTSK protein, human
  • Cathepsin K
  • cruzipain

Grants and funding

This work was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (grant number No. 2018/03911-8 to LHA and 2016/24587-9 to JEHG), and by Ministério da Educação Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) (grant number 031/2013 PRÓ-DEFESA 3 to LHA and PGP). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.