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| [[Image:1pud.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1pud| PDB=1pud | SCENE= }} | | {{STRUCTURE_1pud| PDB=1pud | SCENE= }} |
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| '''TRNA-GUANINE TRANSGLYCOSYLASE'''
| | ===TRNA-GUANINE TRANSGLYCOSYLASE=== |
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| ==Overview==
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| tRNA-guanine transglycosylases (TGT) are enzymes involved in the modification of the anticodon of tRNAs specific for Asn, Asp, His and Tyr, leading to the replacement of guanine-34 at the wobble position by the hypermodified base queuine. In prokaryotes TGT catalyzes the exchange of guanine-34 with the queuine (.)precursor 7-aminomethyl-7-deazaguanine (preQ1). The crystal structure of TGT from Zymomonas mobilis was solved by multiple isomorphous replacement and refined to a crystallographic R-factor of 19% at 1.85 angstrom resolution. The structure consists of an irregular (beta/alpha)8-barrel with a tightly attached C-terminal zinc-containing subdomain. The packing of the subdomain against the barrel is mediated by an alpha-helix, located close to the C-terminus, which displaces the eighth helix of the barrel. The structure of TGT in complex with preQ1 suggests a binding mode for tRNA where the phosphate backbone interacts with the zinc subdomain and the U33G34U35 sequence is recognized by the barrel. This model for tRNA binding is consistent with a base exchange mechanism involving a covalent tRNA-enzyme intermediate. This structure is the first example of a (beta/alpha)-barrel protein interacting specifically with a nucleic acid.
| | The line below this paragraph, {{ABSTRACT_PUBMED_8654383}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 8654383 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_8654383}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Transferase]] | | [[Category: Transferase]] |
| [[Category: Trna-modifying enzyme]] | | [[Category: Trna-modifying enzyme]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:29:37 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 14:07:42 2008'' |
