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1jtf

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[[Image:1jtf.gif|left|200px]]
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{{STRUCTURE_1jtf| PDB=1jtf | SCENE= }}
{{STRUCTURE_1jtf| PDB=1jtf | SCENE= }}
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'''Crystal Structure Analysis of VP39-F180W mutant and m7GpppG complex'''
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===Crystal Structure Analysis of VP39-F180W mutant and m7GpppG complex===
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==Overview==
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The N7-methylguanine portion of the mRNA cap structure interacts with cap-binding proteins via an unusual double-stacking arrangement in which the positively charged cap is sandwiched between two parallel-oriented aromatic protein side chains. Three-dimensional costructures of cap with two mRNA cap-binding proteins, namely, translational initiation factor eIF4E and VP39 (the vaccinia virus-encoded mRNA cap-specific 2'-O-methyltransferase), have heretofore been reported. Despite striking similarities between the two proteins in the double stack with the cap, the stack differs most notably in the species of stacked side chain donated by the protein. Whereas eIF4E employs two tryptophans, VP39 uses a tyrosine and a phenylalanine. Here, we have generated tryptophan substitutions in VP39. Tryptophan substitution was shown, crystallographically, not to disrupt the maintenance of a bona fide parallel stack. However, the single-tryptophan and double-tryptophan substitutions were associated with increased affinity for cap nucleoside by factors of 10 and 50, respectively. VP39 interacted more strongly with a true substrate (containing portions of RNA downstream of the cap in addition to the cap itself) than with isolated cap nucleoside, by several orders of magnitude. VP39 mutants with tryptophan substitution at position 180 exhibited apparent defects in substrate catalytic rate during the first turnover cycle, indicating the possibility of an exquisite sensitivity of the catalytic center to subtle changes in substrate position brought about by alterations in the cap-binding slot. The X-ray structure of VP39 with a genuine nucleobase analogue of N7-methylguanosine, namely, N7,9-dimethylguanine, indicated that the N7-methylguanosine rotational orientation within the stack is a property of the cap nucleobase itself.
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(as it appears on PubMed at http://www.pubmed.gov), where 12056899 is the PubMed ID number.
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{{ABSTRACT_PUBMED_12056899}}
==About this Structure==
==About this Structure==
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[[Category: Mutant]]
[[Category: Mutant]]
[[Category: Vp39]]
[[Category: Vp39]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 21:53:46 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 20:46:32 2008''

Revision as of 17:46, 1 July 2008

Image:1jtf.png

Template:STRUCTURE 1jtf

Crystal Structure Analysis of VP39-F180W mutant and m7GpppG complex

Template:ABSTRACT PUBMED 12056899

About this Structure

1JTF is a Single protein structure of sequence from Vaccinia virus. Full crystallographic information is available from OCA.

Reference

The "cap-binding slot" of an mRNA cap-binding protein: quantitative effects of aromatic side chain choice in the double-stacking sandwich with cap., Hu G, Oguro A, Li C, Gershon PD, Quiocho FA, Biochemistry. 2002 Jun 18;41(24):7677-87. PMID:12056899

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