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1pud
From Proteopedia
(New page: 200px<br /><applet load="1pud" size="450" color="white" frame="true" align="right" spinBox="true" caption="1pud, resolution 1.85Å" /> '''TRNA-GUANINE TRANSGL...) |
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| - | [[Image:1pud.gif|left|200px]]<br /><applet load="1pud" size=" | + | [[Image:1pud.gif|left|200px]]<br /><applet load="1pud" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1pud, resolution 1.85Å" /> | caption="1pud, resolution 1.85Å" /> | ||
'''TRNA-GUANINE TRANSGLYCOSYLASE'''<br /> | '''TRNA-GUANINE TRANSGLYCOSYLASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | tRNA-guanine transglycosylases (TGT) are enzymes involved in the | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1PUD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Zymomonas_mobilis Zymomonas mobilis] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Queuine_tRNA-ribosyltransferase Queuine tRNA-ribosyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.2.29 2.4.2.29] Full crystallographic information is available from [http:// | + | 1PUD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Zymomonas_mobilis Zymomonas mobilis] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Queuine_tRNA-ribosyltransferase Queuine tRNA-ribosyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.2.29 2.4.2.29] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PUD OCA]. |
==Reference== | ==Reference== | ||
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[[Category: trna-modifying enzyme]] | [[Category: trna-modifying enzyme]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:32:39 2008'' |
Revision as of 12:32, 21 February 2008
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TRNA-GUANINE TRANSGLYCOSYLASE
Overview
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.
About this Structure
1PUD is a Single protein structure of sequence from Zymomonas mobilis with as ligand. Active as Queuine tRNA-ribosyltransferase, with EC number 2.4.2.29 Full crystallographic information is available from OCA.
Reference
Crystal structure of tRNA-guanine transglycosylase: RNA modification by base exchange., Romier C, Reuter K, Suck D, Ficner R, EMBO J. 1996 Jun 3;15(11):2850-7. PMID:8654383
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