4wry

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== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
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Uracil N-glycosylase (Ung) is the most thoroughly studied of the group of uracil DNA-glycosylase (UDG) enzymes that catalyse the first step in the uracil excision-repair pathway. The overall structure of the enzyme from Mycobacterium tuberculosis is essentially the same as that of the enzyme from other sources. However, differences exist in the N- and C-terminal stretches and some catalytic loops. Comparison with appropriate structures indicate that the two-domain enzyme closes slightly when binding to DNA, while it opens slightly when binding to the proteinaceous inhibitor Ugi. The structural changes in the catalytic loops on complexation reflect the special features of their structure in the mycobacterial protein. A comparative analysis of available sequences of the enzyme from different sources indicates high conservation of amino-acid residues in the catalytic loops. The uracil-binding pocket in the structure is occupied by a citrate ion. The interactions of the citrate ion with the protein mimic those of uracil, in addition to providing insights into other possible interactions that inhibitors could be involved in.
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17 independent crystal structures of family I uracil-DNA glycosylase from Mycobacterium tuberculosis (MtUng) and its complexes with uracil and its derivatives, distributed among five distinct crystal forms, have been determined. Thermodynamic parameters of binding in the complexes have been measured using isothermal titration calorimetry. The two-domain protein exhibits open and closed conformations, suggesting that the closure of the domain on DNA binding involves conformational selection. Segmental mobility in the enzyme molecule is confined to a 32-residue stretch which plays a major role in DNA binding. Uracil and its derivatives can bind to the protein in two possible orientations. Only one of them is possible when there is a bulky substituent at the 5' position. The crystal structures of the complexes provide a reasonable rationale for the observed thermodynamic parameters. In addition to providing fresh insights into the structure, plasticity and interactions of the protein molecule, the results of the present investigation provide a platform for structure-based inhibitor design.
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Structure of uracil-DNA glycosylase from Mycobacterium tuberculosis: insights into interactions with ligands.,Kaushal PS, Talawar RK, Varshney U, Vijayan M Acta Crystallogr Sect F Struct Biol Cryst Commun. 2010 Aug 1;66(Pt, 8):887-92. Epub 2010 Jul 27. PMID:20693660<ref>PMID:20693660</ref>
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Structural plasticity in Mycobacterium tuberculosis uracil-DNA glycosylase (MtUng) and its functional implications.,Arif SM, Geethanandan K, Mishra P, Surolia A, Varshney U, Vijayan M Acta Crystallogr D Biol Crystallogr. 2015 Jul 1;71(Pt 7):1514-27. doi:, 10.1107/S1399004715009311. Epub 2015 Jun 30. PMID:26143923<ref>PMID:26143923</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

Revision as of 08:13, 22 July 2015

Crystal structure of Mycobacterium tuberculosis uracil-DNA glycosylase in complex with 5-fluorouracil(B), Form I

4wry, resolution 1.43Å

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