Isolation, Solution Structure, and Insecticidal Activity of Kalata B2, a Circular Protein with a Twist: Do Möbius Strips Exist in Nature?
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- 作者：Cameron V. Jennings ; K. Johan Rosengren ; Norelle L. Daly ; Manuel Plan ; Jackie Stevens ; Martin J. Scanlon ; Clement Waine ; David G. Norman ; Marilyn A. Anderson ; and David J. Craik
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：January 25, 2005
- 年：2005
- 卷：44
- 期：3
- 页码：851 - 860
- 全文大小：565K
- 年卷期：v.44,no.3(January 25, 2005)
- ISSN：1520-4995
文摘
A large number of macrocyclic miniproteins with diverse biological activities have been isolatedfrom the Rubiaceae, Violaceae, and Cucurbitaceae plant families in recent years. Here we report thethree-dimensional structure determined using 1H NMR spectroscopy and demonstrate potent insecticidalactivity for one of these peptides, kalata B2. This peptide is one of the major components of an extractfrom the leaves of the plant Oldenlandia affinis. The structure consists of a distorted triple-stranded 
-sheetand a cystine knot arrangement of the disulfide bonds and is similar to those described for other membersof the cyclotide family. The unique cyclic and knotted nature of these molecules makes them a fascinatingexample of topologically complex proteins. Examination of the sequences reveals that they can be separatedinto two subfamilies, one of which contains a larger number of positively charged residues and has abracelet-like circularization of the backbone. The second subfamily contains a backbone twist due to acis-peptidyl-proline bond and may conceptually be regarded as a molecular Möbius strip. Kalata B2 isthe second putative member of the Möbius cyclotide family to be structurally characterized and has acis-peptidyl-proline bond, thus validating the suggested name for this subfamily of cyclotides. Theobservation that kalata B2 inhibits the growth and development of Helicoverpa armigera larvae suggestsa role for the cyclotides in plant defense. A comparison of the sequences and structures of kalata B1 andB2 provides insight into the biological activity of these peptides.
-sheetand a cystine knot arrangement of the disulfide bonds and is similar to those described for other membersof the cyclotide family. The unique cyclic and knotted nature of these molecules makes them a fascinatingexample of topologically complex proteins. Examination of the sequences reveals that they can be separatedinto two subfamilies, one of which contains a larger number of positively charged residues and has abracelet-like circularization of the backbone. The second subfamily contains a backbone twist due to acis-peptidyl-proline bond and may conceptually be regarded as a molecular Möbius strip. Kalata B2 isthe second putative member of the Möbius cyclotide family to be structurally characterized and has acis-peptidyl-proline bond, thus validating the suggested name for this subfamily of cyclotides. Theobservation that kalata B2 inhibits the growth and development of Helicoverpa armigera larvae suggestsa role for the cyclotides in plant defense. A comparison of the sequences and structures of kalata B1 andB2 provides insight into the biological activity of these peptides.