Macromolecule Content

• Total Structure Weight: 3.31 kDa 
• Atom Count: 224 
• Modelled Residue Count: 31 
• Deposited Residue Count: 31 
• Unique protein chains: 1

2B38

Solution structure of kalata B8

• DOI: 10.2210/pdb2B38/pdb
• BMRB: 6872

• Classification: PLANT PROTEIN
• Organism(s): Oldenlandia affinis
• Mutation(s): No 


• Deposited: 2005-09-19 Released: 2006-01-31 
• Deposition Author(s): Daly, N.L., Clark, R.J., Plan, M.R., Craik, D.J.

---

Experimental Data Snapshot

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

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

• PubMed: 16207177 
• 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. 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

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
kalata B8	A	31	Oldenlandia affinis	Mutation(s): 0
UniProt
Find proteins for P85175 (Oldenlandia affinis) Explore P85175  Go to UniProtKB:  P85175

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

Entry History 

Deposition Data

• Deposited Date: 2005-09-19 
• Released Date: 2006-01-31 
Deposition Author(s): Daly, N.L., Clark, R.J., Plan, M.R., Craik, D.J.

Revision History  

• 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