From Proteopedia
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| - | [[Image:1yf8.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1yf8| PDB=1yf8 | SCENE= }} | | {{STRUCTURE_1yf8| PDB=1yf8 | SCENE= }} |
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| - | '''Crystal structure of Himalayan mistletoe RIP reveals the presence of a natural inhibitor and a new functionally active sugar-binding site'''
| + | ===Crystal structure of Himalayan mistletoe RIP reveals the presence of a natural inhibitor and a new functionally active sugar-binding site=== |
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| - | ==Overview==
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| - | Ribosome-inactivating proteins (RIPs) are toxins involved in plant defense. How the plant prevents autotoxicity is not yet fully understood. The present study is the first structural evidence of a naturally inhibited form of RIP from a plant. Himalayan mistletoe RIP (HmRIP) was purified from Viscum album leaves and crystallized with lactose. The structure was determined by the molecular replacement method and refined at 2.8-A resolution. The crystal structure revealed the presence of high quality non-protein electron density at the active site, into which a pteridine derivative (2-amino 4-isopropyl 6-carboxyl pteridine) was modeled. The carboxyl group of the ligand binds strongly with the key active site residue Arg(162), nullifies the positive charge required for catalysis, and thereby acts as a natural inhibitor. Lectin subunits of RIPs have two active sugar-binding sites present in 1alpha- and 2gamma-subdomains. A third functionally active site has been identified in the 1beta-subdomain of HmRIP. The 1beta-site is active despite the absence of conserved polar sugar-binding residues. Loss of these residues is compensated by the following: (i) the presence of an extended site where the penultimate sugar also interacts with the protein; (ii) the interactions of galactose with the protein main chain carbonyl and amide nitrogen atoms; (iii) the presence of a well defined pocket encircled by four walls; and (iv) a favorable stacking of the galactose ring with Tyr(66) besides the conserved Phe(75). The mode of sugar binding is also distinct at the 1alpha and 2gamma sugar-binding sites.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_15774467}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15774467 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15774467}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Sugar-binding site]] | | [[Category: Sugar-binding site]] |
| | [[Category: Viscum album]] | | [[Category: Viscum album]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:14:51 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 14:24:27 2008'' |
Revision as of 11:24, 28 July 2008
Template:STRUCTURE 1yf8
Crystal structure of Himalayan mistletoe RIP reveals the presence of a natural inhibitor and a new functionally active sugar-binding site
Template:ABSTRACT PUBMED 15774467
About this Structure
1YF8 is a Protein complex structure of sequences from Viscum album. Full crystallographic information is available from OCA.
Reference
Crystal structure of himalayan mistletoe ribosome-inactivating protein reveals the presence of a natural inhibitor and a new functionally active sugar-binding site., Mishra V, Bilgrami S, Sharma RS, Kaur P, Yadav S, Krauspenhaar R, Betzel C, Voelter W, Babu CR, Singh TP, J Biol Chem. 2005 May 27;280(21):20712-21. Epub 2005 Mar 17. PMID:15774467
Page seeded by OCA on Mon Jul 28 14:24:27 2008
