MIC5 regulates the activity of Toxoplasma subtilisin 1 by mimicking a subtilisin prodomain

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 10 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation   3D Report Full Report

This is version 1.3 of the entry. See complete history


Microneme protein 5 regulates the activity of toxoplasma subtilisin 1 by mimicking a subtilisin prodomain.

Saouros, S.Dou, Z.Henry, M.Marchant, J.Carruthers, V.B.Matthews, S.

(2012) J Biol Chem 287: 36029-36040

  • DOI: https://doi.org/10.1074/jbc.M112.389825
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Toxoplasma gondii is the model parasite of the phylum Apicomplexa, which contains obligate intracellular parasites of medical and veterinary importance. Apicomplexans invade host cells by a multistep process involving the secretion of adhesive microneme protein (MIC) complexes. The subtilisin protease TgSUB1 trims several MICs on the parasite surface to activate gliding motility and host invasion. Although a previous study showed that expression of the secretory protein TgMIC5 suppresses TgSUB1 activity, the mechanism was unknown. Here, we solve the three-dimensional structure of TgMIC5 by nuclear magnetic resonance (NMR), revealing that it mimics a subtilisin prodomain including a flexible C-terminal peptide that may insert into the subtilisin active site. We show that TgMIC5 is an almost 50-fold more potent inhibitor of TgSUB1 activity than the small molecule inhibitor N-[N-(N-acetyl-L-leucyl)-L-leucyl]-L-norleucine (ALLN). Moreover, we demonstrate that TgMIC5 is retained on the parasite plasma membrane via its physical interaction with the membrane-anchored TgSUB1.

  • Organizational Affiliation

    Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Microneme TgMIC5 protein138Toxoplasma gondiiMutation(s): 0 
Gene Names: TGME49_077080TGVEG_027740
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 10 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-08-22
    Type: Initial release
  • Version 1.1: 2012-11-14
    Changes: Database references
  • Version 1.2: 2023-06-14
    Changes: Data collection, Database references, Other
  • Version 1.3: 2024-05-15
    Changes: Data collection, Database references