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4qdf
From Proteopedia
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<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4qdf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4qdf OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4qdf RCSB], [http://www.ebi.ac.uk/pdbsum/4qdf PDBsum]</span></td></tr> | <tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4qdf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4qdf OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4qdf RCSB], [http://www.ebi.ac.uk/pdbsum/4qdf PDBsum]</span></td></tr> | ||
<table> | <table> | ||
| + | <div style="background-color:#fffaf0;"> | ||
| + | == Publication Abstract from PubMed == | ||
| + | KshA is the oxygenase component of 3-ketosteroid 9alpha-hydroxylase, a Rieske oxygenase involved in the bacterial degradation of steroids. Consistent with its role in bile acid catabolism, KshA1 from Rhodococcus rhodochrous DSM43269 had the highest apparent specificity (kcat/Km) for steroids with an isopropyl side chain at C17, such as 3-oxo-23,24-bisnorcholesta-1,4-diene-22-oate (1,4-BNC). By contrast, the KshA5 homolog had the highest apparent specificity for substrates with no C17 side chain (kcat/Km >10(5) s(-1) m(-1) for 4-estrendione, 5alpha-androstandione, and testosterone). Unexpectedly, substrates such as 4-androstene-3,17-dione (ADD) and 4-BNC displayed strong substrate inhibition (Ki S approximately 100 mum). By comparison, the cholesterol-degrading KshAMtb from Mycobacterium tuberculosis had the highest specificity for CoA-thioesterified substrates. These specificities are consistent with differences in the catabolism of cholesterol and bile acids, respectively, in actinobacteria. X-ray crystallographic structures of the KshAMtb.ADD, KshA1.1,4-BNC-CoA, KshA5.ADD, and KshA5.1,4-BNC-CoA complexes revealed that the enzymes have very similar steroid-binding pockets with the substrate's C17 oriented toward the active site opening. Comparisons suggest Tyr-245 and Phe-297 are determinants of KshA1 specificity. All enzymes have a flexible 16-residue "mouth loop," which in some structures completely occluded the substrate-binding pocket from the bulk solvent. Remarkably, the catalytic iron and alpha-helices harboring its ligands were displaced up to 4.4 A in the KshA5.substrate complexes as compared with substrate-free KshA, suggesting that Rieske oxygenases may have a dynamic nature similar to cytochrome P450. | ||
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| + | Substrate specificities and conformational flexibility of 3-ketosteroid 9alpha-hydroxylases.,Penfield JS, Worrall LJ, Strynadka NC, Eltis LD J Biol Chem. 2014 Sep 12;289(37):25523-36. doi: 10.1074/jbc.M114.575886. Epub, 2014 Jul 21. PMID:25049233<ref>PMID:25049233</ref> | ||
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| + | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | ||
| + | </div> | ||
| + | == References == | ||
| + | <references/> | ||
__TOC__ | __TOC__ | ||
</StructureSection> | </StructureSection> | ||
Revision as of 21:55, 1 October 2014
Crystal structure of apo KshA5 and KshA1 in complex with 1,4-30Q-CoA from R. rhodochrous
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