1tw3

<table><tr><td colspan='2'>[[1tw3]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/As_4.1799 As 4.1799]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TW3 OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=1TW3 FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ERT:METHYL+(4R)-2-ETHYL-2,5,12-TRIHYDROXY-7-METHOXY-6,11-DIOXO-4-{[2,3,6-TRIDEOXY-3-(DIMETHYLAMINO)-BETA-D-RIBO-HEXOPYRANOSYL]OXY}-1H,2H,3H,4H,6H,11H-TETRACENE-1-CARBOXYLATE'>ERT</scene>, <scene name='pdbligand=SAH:S-ADENOSYL-L-HOMOCYSTEINE'>SAH</scene></td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">dnrk ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1950 AS 4.1799])</td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://proteopedia.org/fgij/fg.htm?mol=1tw3 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1tw3 OCA], [http://pdbe.org/1tw3 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1tw3 RCSB], [http://www.ebi.ac.uk/pdbsum/1tw3 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1tw3 ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/DNRK_STRPE DNRK_STRPE]] Involved in the biosynthesis of the anthracyclines carminomycin and daunorubicin (daunomycin) which are aromatic polyketide antibiotics that exhibit high cytotoxicity and are widely applied in the chemotherapy of a variety of cancers. In vivo, catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to the 4-O-position of carminomycin to form daunorubicin. In vitro, it also methylates the anthracyclines rhodomycin D (10-carbomethoxy-13-deoxycarminomycin) and 13-deoxy-carminomycin at the 4-hydroxyl position. It is quite specific with respect to the length of the carbohydrate chain at the C7 position, but it can accept substrates with bulky substituent at C10 position.<ref>PMID:15273252</ref>

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== Publication Abstract from PubMed ==

One of the final steps in the biosynthesis of the widely used anti-tumor drug daunorubicin in Streptomyces peucetius is the methylation of the 4-hydroxyl group of the tetracyclic ring system. This reaction is catalyzed by the S-adenosyl-L-methionine-dependent carminomycin 4-O-methyltransferase DnrK. The crystal structure of the ternary complex of this enzyme with the bound products S-adenosyl-L-homocysteine and 4-methoxy-epsilon-rhodomycin T has been determined to a 2.35-angstroms resolution. DnrK is a homodimer, and the subunit displays the typical fold of small molecule O-methyltransferases. The structure provides insights into the recognition of the anthracycline substrate and also suggests conformational changes as part of the catalytic cycle of the enzyme. The position and orientation of the bound ligands are consistent with an SN2 mechanism of methyl transfer. Mutagenesis experiments on a putative catalytic base confirm that DnrK most likely acts as an entropic enzyme in that rate enhancement is mainly due to orientational and proximity effects. This contrasts the mechanism of DnrK with that of other O-methyltransferases where acid/base catalysis has been demonstrated to be an essential contribution to rate enhancement.

Crystal structure of a ternary complex of DnrK, a methyltransferase in daunorubicin biosynthesis, with bound products.,Jansson A, Koskiniemi H, Mantsala P, Niemi J, Schneider G J Biol Chem. 2004 Sep 24;279(39):41149-56. Epub 2004 Jul 24. PMID:15273252<ref>PMID:15273252</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 1tw3" style="background-color:#fffaf0;"></div>

[[Category: As 4 1799]]

[[Category: Jansson, A]]

[[Category: Koskiniemi, H]]

[[Category: Mantsala, P]]

[[Category: Niemi, J]]

[[Category: Schneider, G]]

[[Category: Transferase]]