2B38

Solution structure of kalata B8

2B38 の概要

• エントリーDOI: 10.2210/pdb2b38/pdb
• NMR情報: BMRB: 6872
• 分子名称: kalata B8 (1 entity in total)
• 機能のキーワード: cyclic backbone, cystine knot, beta-hairpin, plant protein
• 由来する生物種: Oldenlandia affinis
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 3310.82

構造登録者

Daly, N.L.,Clark, R.J.,Plan, M.R.,Craik, D.J. (登録日: 2005-09-19, 公開日: 2006-01-31, 最終更新日: 2024-10-30)

主引用文献

Daly, N.L.,Clark, R.J.,Plan, M.R.,Craik, D.J.
Kalata B8, a novel antiviral circular protein, exhibits conformational flexibility in the cystine knot motif
Biochem.J., 393:619-626, 2006

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.

PubMed: 16207177
DOI: 10.1042/BJ20051371

実験手法

SOLUTION NMR