1IB9

SOLUTION STRUCTURE OF MCOTI-II, A MACROCYCLIC TRYPSIN INHIBITOR


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: The submitted conformer models are those with the fewest number of restraint violations. 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Circular proteins in plants: solution structure of a novel macrocyclic trypsin inhibitor from Momordica cochinchinensis.

Felizmenio-Quimio, M.E.Daly, N.L.Craik, D.J.

(2001) J Biol Chem 276: 22875-22882

  • DOI: 10.1074/jbc.M101666200
  • Primary Citation of Related Structures:  
    1IB9

  • PubMed Abstract: 
  • Much interest has been generated by recent reports on the discovery of circular (i.e. head-to-tail cyclized) proteins in plants. Here we report the three-dimensional structure of one of the newest such circular proteins, MCoTI-II, a novel trypsin inhibitor from Momordica cochinchinensis, a member of the Cucurbitaceae plant family ...

    Much interest has been generated by recent reports on the discovery of circular (i.e. head-to-tail cyclized) proteins in plants. Here we report the three-dimensional structure of one of the newest such circular proteins, MCoTI-II, a novel trypsin inhibitor from Momordica cochinchinensis, a member of the Cucurbitaceae plant family. The structure consists of a small beta-sheet, several turns, and a cystine knot arrangement of the three disulfide bonds. Interestingly, the molecular topology is similar to that of the plant cyclotides (Craik, D. J., Daly, N. L., Bond, T., and Waine, C. (1999) J. Mol. Biol. 294, 1327-1336), which derive from the Rubiaceae and Violaceae plant families, have antimicrobial activities, and exemplify the cyclic cystine knot structural motif as part of their circular backbone. The sequence, biological activity, and plant family of MCoTI-II are all different from known cyclotides. However, given the structural similarity, cyclic backbone, and plant origin of MCoTI-II, we propose that MCoTI-II can be classified as a new member of the cyclotide class of proteins. The expansion of the cyclotides to include trypsin inhibitory activity and a new plant family highlights the importance and functional variability of circular proteins and the fact that they are more common than has previously been believed. Insights into the possible roles of backbone cyclization have been gained by a comparison of the structure of MCoTI-II with the homologous acyclic trypsin inhibitors CMTI-I and EETI-II from the Cucurbitaceae plant family.


    Organizational Affiliation

    Institute for Molecular Bioscience, University of Queensland, Brisbane, 4072 Queensland, Australia.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
TRYPSIN INHIBITOR IIA34Momordica cochinchinensisMutation(s): 0 
UniProt
Find proteins for P82409 (Momordica cochinchinensis)
Explore P82409 
Go to UniProtKB:  P82409
Protein Feature View
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  • Reference Sequence
Biologically Interesting Molecules (External Reference) 1 Unique
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: The submitted conformer models are those with the fewest number of restraint violations. 
  • OLDERADO: 1IB9 Olderado

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2001-07-18
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2013-02-27
    Changes: Other