4mzu

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=COA:COENZYME+A'>COA</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=TDR:THYMINE'>TDR</scene>, <scene name='pdbligand=TYD:THYMIDINE-5-DIPHOSPHATE'>TYD</scene></td></tr>

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== Publication Abstract from PubMed ==

Unusual N-acetylated sugars have been observed on the O-antigens of some Gram-negative bacteria and on the S-layers of both Gram-positive and Gram-negative bacteria. One such sugar is 3-acetamido-3,6-dideoxy-alpha-d-galactose or Fuc3NAc. The pathway for its production requires five enzymes with the first step involving the attachment of dTMP to glucose-1-phosphate. Here, we report a structural and biochemical characterization of a bifunctional enzyme from Shewanella denitificans thought to be involved in the biosynthesis of dTDP-Fuc3NAc. On the basis of a bioinformatics analysis, the enzyme, hereafter referred to as FdtD, has been postulated to catalyze the third and fifth steps in the pathway, namely, a 3,4-keto isomerization and an N-acetyltransferase reaction. For the X-ray analysis reported here, the enzyme was crystallized in the presence of dTDP and CoA. The crystal structure shows that FdtD adopts a hexameric quaternary structure with 322 symmetry. Each subunit of the hexamer folds into two distinct domains connected by a flexible loop. The N-terminal domain adopts a left-handed beta-helix motif and is responsible for the N-acetylation reaction. The C-terminal domain folds into an antiparallel flattened beta-barrel that harbors the active site responsible for the isomerization reaction. Biochemical assays verify the two proposed catalytic activities of the enzyme and reveal that the 3,4-keto isomerization event leads to the inversion of configuration about the hexose C-4' carbon.

Structural and Biochemical Characterization of a Bifunctional Ketoisomerase/N-Acetyltransferase from Shewanella denitrificans.,Chantigian DP, Thoden JB, Holden HM Biochemistry. 2013 Nov 19;52(46):8374-85. doi: 10.1021/bi401170t. Epub 2013 Nov, 4. PMID:24128043<ref>PMID:24128043</ref>

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

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== References ==

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