4QDF

Crystal structure of apo KshA5 and KshA1 in complex with 1,4-30Q-CoA from R. rhodochrous

4QDF の概要

• エントリーDOI: 10.2210/pdb4qdf/pdb
• 関連するPDBエントリー: 4QCK 4QDC 4QDD
• 分子名称: 3-ketosteroid 9alpha-hydroxylase oxygenase, FE2/S2 (INORGANIC) CLUSTER, FE (II) ION, ... (9 entities in total)
• 機能のキーワード: mixed function oxygenases, oxidoreductase-oxidoreductase inhibitor complex, oxidoreductase/oxidoreductase inhibitor
• 由来する生物種: Rhodococcus rhodochrous; 詳細
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 90673.70

構造登録者

Penfield, J.,Worrall, L.J.,Strynadka, N.C.,Eltis, L.D. (登録日: 2014-05-13, 公開日: 2014-07-30, 最終更新日: 2024-02-28)

主引用文献

Penfield, J.S.,Worrall, L.J.,Strynadka, N.C.,Eltis, L.D.
Substrate specificities and conformational flexibility of 3-ketosteroid 9 alpha-hydroxylases.
J.Biol.Chem., 289:25523-25536, 2014

PubMed Abstract: KshA is the oxygenase component of 3-ketosteroid 9α-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, 5α-androstandione, and testosterone). Unexpectedly, substrates such as 4-androstene-3,17-dione (ADD) and 4-BNC displayed strong substrate inhibition (Ki S ∼100 μM). 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 α-helices harboring its ligands were displaced up to 4.4 Å in the KshA5·substrate complexes as compared with substrate-free KshA, suggesting that Rieske oxygenases may have a dynamic nature similar to cytochrome P450.

PubMed: 25049233
DOI: 10.1074/jbc.M114.575886

実験手法

X-RAY DIFFRACTION (2.43 Å)