3g77

<StructureSection load='3g77' size='340' side='right' caption='[[3g77]], [[Resolution|resolution]] 1.80&Aring;' scene=''>

<table><tr><td colspan='2'>[[3g77]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Ecoli Ecoli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3G77 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3G77 FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=FE:FE+(III)+ION'>FE</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1rb7|1rb7]], [[1rak|1rak]], [[1ra0|1ra0]], [[1r9z|1r9z]], [[1r9y|1r9y]], [[1k6w|1k6w]]</td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">codA, b0337, JW0328 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=83333 ECOLI])</td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Cytosine_deaminase Cytosine deaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.4.1 3.5.4.1] </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=3g77 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3g77 OCA], [http://pdbe.org/3g77 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3g77 RCSB], [http://www.ebi.ac.uk/pdbsum/3g77 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=3g77 ProSAT]</span></td></tr>

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== Publication Abstract from PubMed ==

Cytosine deaminase is used in combination with 5-fluorocytosine as an enzyme-prodrug combination for targeted genetic cancer treatment. This approach is limited by inefficient gene delivery and poor prodrug conversion activities. Previously, we reported individual point mutations within the substrate binding pocket of bacterial cytosine deaminase (bCD) that result in marginal improvements in the ability to sensitize cells to 5-fluorocytosine (5FC). Here, we describe an expanded random mutagenesis and selection experiment that yielded enzyme variants, which provide significant improvement in prodrug sensitization. Three of these mutants were evaluated using enzyme kinetic analyses and then assayed in three cancer cell lines for 5FC sensitization, bystander effects, and formation of 5-fluorouracil metabolites. All variants displayed 18- to 19-fold shifts in substrate preference toward 5FC, a significant reduction in IC(50) values and improved bystander effect compared with wild-type bCD. In a xenograft tumor model, the best enzyme mutant was shown to prevent tumor growth at much lower doses of 5FC than is observed when tumor cells express wild-type bCD. Crystallographic analyses of this construct show the basis for improved activity toward 5FC, and also how two different mutagenesis strategies yield closely related but mutually exclusive mutations that each result in a significant alteration of enzyme specificity.

Bacterial cytosine deaminase mutants created by molecular engineering show improved 5-fluorocytosine-mediated cell killing in vitro and in vivo.,Fuchita M, Ardiani A, Zhao L, Serve K, Stoddard BL, Black ME Cancer Res. 2009 Jun 1;69(11):4791-9. PMID:19487291<ref>PMID:19487291</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 3g77" style="background-color:#fffaf0;"></div>

*[[Deaminase|Deaminase]]

[[Category: Cytosine deaminase]]

[[Category: Ecoli]]

[[Category: Stoddard, B]]

[[Category: Zhao, L]]

[[Category: Protein engineering]]