2B38

Solution structure of kalata B8


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

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This is version 1.2 of the entry. See complete history


Literature

Kalata B8, a novel antiviral circular protein, exhibits conformational flexibility in the cystine knot motif

Daly, N.L.Clark, R.J.Plan, M.R.Craik, D.J.

(2006) Biochem J 393: 619-626

  • DOI: 10.1042/BJ20051371
  • Primary Citation of Related Structures:  
    2B38

  • PubMed Abstract: 
  • The cyclotides are a family of circular proteins with a range of biological activities and potential pharmaceutical and agricultural applications. The biosynthetic mechanism of cyclization is unknown and the discovery of novel sequences may assist in achieving this goal ...

    The cyclotides are a family of circular proteins with a range of biological activities and potential pharmaceutical and agricultural applications. The biosynthetic mechanism of cyclization is unknown and the discovery of novel sequences may assist in achieving this goal. In the present study, we have isolated a new cyclotide from Oldenlandia affinis, kalata B8, which appears to be a hybrid of the two major subfamilies (Möbius and bracelet) of currently known cyclotides. We have determined the three-dimensional structure of kalata B8 and observed broadening of resonances directly involved in the cystine knot motif, suggesting flexibility in this region despite it being the core structural element of the cyclotides. The cystine knot motif is widespread throughout Nature and inherently stable, making this apparent flexibility a surprising result. Furthermore, there appears to be isomerization of the peptide backbone at an Asp-Gly sequence in the region involved in the cyclization process. Interestingly, such isomerization has been previously characterized in related cyclic knottins from Momordica cochinchinensis that have no sequence similarity to kalata B8 apart from the six conserved cysteine residues and may result from a common mechanism of cyclization. Kalata B8 also provides insight into the structure-activity relationships of cyclotides as it displays anti-HIV activity but lacks haemolytic activity. The 'uncoupling' of these two activities has not previously been observed for the cyclotides and may be related to the unusual hydrophilic nature of the peptide.


    Organizational Affiliation

    Institute for Molecular Bioscience, Australian Research Council Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane, QLD 4072, Australia.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
kalata B8A31Oldenlandia affinisMutation(s): 0 
UniProt
Find proteins for P85175 (Oldenlandia affinis)
Explore P85175 
Go to UniProtKB:  P85175
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 
  • OLDERADO: 2B38 Olderado

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-01-31
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance