View source for 8iij


==H109G mutant of uracil DNA glycosylase X==
<StructureSection load='8iij' size='340' side='right'caption='[[8iij]], [[Resolution|resolution]] 1.83&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8iij]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Mycolicibacterium_smegmatis_MC2_155 Mycolicibacterium smegmatis MC2 155]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8IIJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8IIJ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.83&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BME:BETA-MERCAPTOETHANOL'>BME</scene>, <scene name='pdbligand=SF4:IRON/SULFUR+CLUSTER'>SF4</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=8iij FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8iij OCA], [https://pdbe.org/8iij PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8iij RCSB], [https://www.ebi.ac.uk/pdbsum/8iij PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8iij ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A0QP43_MYCS2 A0QP43_MYCS2] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
UdgX excises uracil from uracil-containing DNA to concurrently form a covalent bond with the resulting AP-DNA. Structurally, UdgX is highly similar to family-4 UDGs (F4-UDGs). However, UdgX is unique in possessing a flexible R-loop (105KRRIH109). Among the class-defining motifs, while its motif A (51GEQPG55) diverged to possess Q53 in place of A53/G53 in F4-UDGs, motif B [178HPS(S/A)(L/V)(L/V)R184] has remained unchanged. Previously, we proposed an SN1 mechanism resulting in a covalent bond between H109 and AP-DNA. In this study, we investigated several single/double mutants of UdgX. The H109A, H109S, H109G, H109Q, H109C and H109K mutants gain conventional UDG activity to varying levels. The crystal structures of UdgX mutants show topological changes in their active sites, rationalizing their UDG activities. The E52Q, E52N and E52A mutants reveal that E52 forms a catalytic dyad with H109 to enhance its nucleophilicity. The Q53A mutant supports that UdgX specific evolution of Q53 occurred essentially to stabilize the R-loop conformation. The R184A mutation (motif B) supports the role of R184 in substrate-binding. Taken together, the structural, bioinformatics, and mutational studies suggest that UdgX diverged from F4-UDGs, and the emergence of the characteristic R-loop in UdgX is functionally assisted by A53/G53 to Q53 changes in motif A.

Mutational and structural analyses of UdgX: insights into the active site pocket architecture and its evolution.,Aroli S, Woo EJ, Gopal B, Varshney U Nucleic Acids Res. 2023 Jul 21;51(13):6554-6565. doi: 10.1093/nar/gkad486. PMID:37283083<ref>PMID:37283083</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 8iij" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Mycolicibacterium smegmatis MC2 155]]
[[Category: Aroli S]]