1HA9

SOLUTION STRUCTURE OF THE SQUASH TRYPSIN INHIBITOR MCoTI-II, NMR, 30 STRUCTURES.


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 30 
  • Conformers Submitted: 30 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Solution Structure of the Squash Trypsin Inhibitor Mcoti-II. A New Family for Cyclic Knottins

Heitz, A.Hernandez, J.-F.Gagnon, J.Hong, T.T.Pham, T.T.C.Nguyen, T.M.Le-Nguyen, D.Chiche, L.

(2001) Biochemistry 40: 7973


  • PubMed Abstract: 
  • The "knottin" fold is a stable cysteine-rich scaffold, in which one disulfide crosses the macrocycle made by two other disulfides and the connecting backbone segments. This scaffold is found in several protein families with no evolutionary relationsh ...

    The "knottin" fold is a stable cysteine-rich scaffold, in which one disulfide crosses the macrocycle made by two other disulfides and the connecting backbone segments. This scaffold is found in several protein families with no evolutionary relationships. In the past few years, several homologous peptides from the Rubiaceae and Violaceae families were shown to define a new structural family based on macrocyclic knottin fold. We recently isolated from Momordica cochinchinensis seeds the first known macrocyclic squash trypsin inhibitors. These compounds are the first members of a new family of cyclic knottins. In this paper, we present NMR structural studies of one of them, MCoTI-II, and of a beta-Asp rearranged form, MCoTI-IIb. Both compounds display similar and well-defined conformations. These cyclic squash inhibitors share a similar conformation with noncyclic squash inhibitors such as CPTI-II, and it is postulated that the main effect of the cyclization is a reduced sensitivity to exo-proteases. On the contrary, clear differences were detected with the three-dimensional structures of other known cyclic knottins, i.e., kalata B1 or circulin A. The two-disulfide cystine-stabilized beta-sheet motif [Heitz et al. (1999) Biochemistry 38, 10615-10625] is conserved in the two families, whereas in the C-to-N linker, one disulfide bridge and one loop are differently located. The molecular surface of MCoTI-II is almost entirely charged in contrast to circulin A that displays a well-marked amphiphilic character. These differences might explain why the isolated macrocyclic squash inhibitors from M. cochinchinensis display no significant antibacterial activity, whereas circulins and kalata B1 do.


    Organizational Affiliation

    Centre de Biochimie Structurale, UMR5048 CNRS-Université Montpellier I, UMR554 INSERM-Université Montpellier I, Faculté de pharmacie, 15 avenue Charles Flahault, 34060 Montpellier, France.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
TRYPSIN INHIBITOR II
A
34Momordica cochinchinensisMutation(s): 0 
Find proteins for P82409 (Momordica cochinchinensis)
Go to UniProtKB:  P82409
Small Molecules
Biologically Interesting Molecules 1 Unique
IDChainsNameType/Class2D Diagram3D Interactions
PRD_000750
Query on PRD_000750
ACYCLIC KNOTTIN TRYPSIN INHIBITOR IICyclic peptide / Antimicrobial, Antitumor

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Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 30 
  • Conformers Submitted: 30 
  • Olderado: 1HA9 Olderado

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-04-12
    Type: Initial release
  • Version 1.1: 2012-11-30
    Type: Other