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1pxg

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Revision as of 16:09, 12 October 2017

Crystal structure of the mutated tRNA-guanine transglycosylase (TGT) D280E complexed with preQ1

Structural highlights

1pxg is a 1 chain structure with sequence from "achromobacter_anaerobium"_(sic)_shimwell_1937 "achromobacter anaerobium" (sic) shimwell 1937. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Ligands:	, ,
Gene:	TGT ("Achromobacter anaerobium" (sic) Shimwell 1937)
Activity:	tRNA-guanine(34) transglycosylase, with EC number 2.4.2.29
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

[TGT_ZYMMO] Exchanges the guanine residue with 7-aminomethyl-7-deazaguanine in tRNAs with GU(N) anticodons (tRNA-Asp, -Asn, -His and -Tyr). After this exchange, a cyclopentendiol moiety is attached to the 7-aminomethyl group of 7-deazaguanine, resulting in the hypermodified nucleoside queuosine (Q) (7-(((4,5-cis-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-7-deazaguanosine).[HAMAP-Rule:MF_00168]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

tRNA-guanine transglycosylase (TGT) catalyzes a post-transcriptional base-exchange reaction involved in the incorporation of the modified base queuine (Q) into the wobble position of certain tRNAs. Catalysis by TGT occurs through a double-displacement mechanism that involves the formation of a covalent enzyme-RNA intermediate (Kittendorf, J. D., Barcomb, L. M., Nonekowski, S. T., and Garcia, G. A. (2001) Biochemistry 40, 14123-14133). The TGT chemical mechanism requires the protonation of the displaced guanine and the deprotonation of the incoming heterocyclic base. Based on its position in the active site, it is likely that aspartate 264 is involved in these proton transfer events. To investigate this possibility, site-directed mutagenesis was employed to convert aspartate 264 to alanine, asparagine, glutamate, glutamine, lysine, and histidine. Biochemical characterization of these TGT mutants revealed that only the conservative glutamate mutant retained catalytic activity, with Km values for both tRNA and guanine 3-fold greater than those for wild-type, whereas the kcat was depressed by an order of magnitude. Furthermore, of these six TGT mutants, only the TGT(D264E) was capable of forming a TGT.RNA covalent intermediate; however, unlike wild-type TGT, only hydroxylamine is capable of cleaving the TGT(D264E).RNA covalent complex. In an effort to better understand the unique biochemical properties of the D264E TGT mutant, we solved the crystal structure of the Zymomonas mobilis TGT with the analogous mutation (D280E). The results of these studies support two roles for aspartate 264 in catalysis by TGT, protonation of the leaving guanine and deprotonation of the incoming preQ1.

An essential role for aspartate 264 in catalysis by tRNA-guanine transglycosylase from Escherichia coli.,Kittendorf JD, Sgraja T, Reuter K, Klebe G, Garcia GA J Biol Chem. 2003 Oct 24;278(43):42369-76. Epub 2003 Aug 8. PMID:12909636^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Kittendorf JD, Sgraja T, Reuter K, Klebe G, Garcia GA. An essential role for aspartate 264 in catalysis by tRNA-guanine transglycosylase from Escherichia coli. J Biol Chem. 2003 Oct 24;278(43):42369-76. Epub 2003 Aug 8. PMID:12909636 doi:http://dx.doi.org/10.1074/jbc.M304323200

1 Structural highlights
2 Function
3 Evolutionary Conservation
4 Publication Abstract from PubMed
5 References

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/1pxg"

@@ Line 1: / Line 1: @@
 ==Crystal structure of the mutated tRNA-guanine transglycosylase (TGT) D280E complexed with preQ1==
 <StructureSection load='1pxg' size='340' side='right' caption='[[1pxg]], [[Resolution|resolution]] 1.70&Aring;' scene=''>
@@ Line 6: / Line 7: @@
 <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">TGT ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=542 "Achromobacter anaerobium" (sic) Shimwell 1937])</td></tr>
 <tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/tRNA-guanine(34)_transglycosylase tRNA-guanine(34) transglycosylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.2.29 2.4.2.29] </span></td></tr>
-<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1pxg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1pxg OCA], [http://pdbe.org/1pxg PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1pxg RCSB], [http://www.ebi.ac.uk/pdbsum/1pxg PDBsum]</span></td></tr>
+<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1pxg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1pxg OCA], [http://pdbe.org/1pxg PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1pxg RCSB], [http://www.ebi.ac.uk/pdbsum/1pxg PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1pxg ProSAT]</span></td></tr>
 </table>
 == Function ==
@@ Line 29: / Line 30: @@
 </div>
 <div class="pdbe-citations 1pxg" style="background-color:#fffaf0;"></div>
-==See Also==
-*[[TRNA-guanine transglycosylase|TRNA-guanine transglycosylase]]
 == References ==
 <references/>

1pxg

From Proteopedia

Revision as of 16:09, 12 October 2017

Crystal structure of the mutated tRNA-guanine transglycosylase (TGT) D280E complexed with preQ1

Structural highlights

Function

Evolutionary Conservation

Publication Abstract from PubMed

References

Contents

Proteopedia Page Contributors and Editors (what is this?)

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