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| {{STRUCTURE_1pt4| PDB=1pt4 | SCENE= }} | | {{STRUCTURE_1pt4| PDB=1pt4 | SCENE= }} |
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| '''Solution structure of the Moebius cyclotide kalata B2'''
| | ===Solution structure of the Moebius cyclotide kalata B2=== |
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| ==Overview==
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| A large number of macrocyclic miniproteins with diverse biological activities have been isolated from the Rubiaceae, Violaceae, and Cucurbitaceae plant families in recent years. Here we report the three-dimensional structure determined using (1)H NMR spectroscopy and demonstrate potent insecticidal activity for one of these peptides, kalata B2. This peptide is one of the major components of an extract from the leaves of the plant Oldenlandia affinis. The structure consists of a distorted triple-stranded beta-sheet and a cystine knot arrangement of the disulfide bonds and is similar to those described for other members of the cyclotide family. The unique cyclic and knotted nature of these molecules makes them a fascinating example of topologically complex proteins. Examination of the sequences reveals that they can be separated into two subfamilies, one of which contains a larger number of positively charged residues and has a bracelet-like circularization of the backbone. The second subfamily contains a backbone twist due to a cis-peptidyl-proline bond and may conceptually be regarded as a molecular Mobius strip. Kalata B2 is the second putative member of the Mobius cyclotide family to be structurally characterized and has a cis-peptidyl-proline bond, thus validating the suggested name for this subfamily of cyclotides. The observation that kalata B2 inhibits the growth and development of Helicoverpa armigera larvae suggests a role for the cyclotides in plant defense. A comparison of the sequences and structures of kalata B1 and B2 provides insight into the biological activity of these peptides.
| | The line below this paragraph, {{ABSTRACT_PUBMED_15654741}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 15654741 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_15654741}} |
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| ==About this Structure== | | ==About this Structure== |
| 1PT4 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oldenlandia_affinis Oldenlandia affinis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PT4 OCA]. | | 1PT4 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oldenlandia_affinis Oldenlandia affinis]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PT4 OCA]. |
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| ==Reference== | | ==Reference== |
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| [[Category: Cyclotide]] | | [[Category: Cyclotide]] |
| [[Category: Kalata]] | | [[Category: Kalata]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:27:33 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 21:44:02 2008'' |
