7EPO

Ketosteroid Isomerase KSI with 5-nitrobenzoxazole (5NBI)

7EPO の概要

• エントリーDOI: 10.2210/pdb7epo/pdb
• 分子名称: SnoaL-like domain-containing protein, 5-nitro-1,2-benzoxazole (3 entities in total)
• 機能のキーワード: kemp elimination, msksi, mycobacterium smegmatis, crystal structure., isomerase
• 由来する生物種: Mycolicibacterium smegmatis (strain ATCC 700084 / mc(2)155) (Mycobacterium smegmatis)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 16558.45

構造登録者

Liang, Y.,Zhang, Q.,Bartlam, M. (登録日: 2021-04-27, 公開日: 2021-12-22, 最終更新日: 2023-11-29)

主引用文献

Liang, Y.,Li, W.,Liang, H.,Lou, X.,Liu, R.,Zhang, Q.,Bartlam, M.
Structural characterization and Kemp eliminase activity of the Mycobacterium smegmatis Ketosteroid Isomerase.
Biochem.Biophys.Res.Commun., 560:159-164, 2021

PubMed Abstract: The Kemp elimination reaction, involving the ring-opening of benzoxazole and its derivatives under the action of natural enzymes or chemical catalysts, has been of interest to researchers since its discovery. Because this reaction does not exist in all currently known metabolic pathways, the computational design of Kemp eliminases has provided valuable insights into principles of enzymatic catalysis. However, it was discovered that the naturally occurring promiscuous enzymes ydbC, xapA and ketosteroid isomerase also can catalyze Kemp elimination. Here, we report the crystal structure of ketosteroid isomerase (KSI) from Mycobacterium smegmatis MC2 155. MsKSI crystallizes in the P222 space group with two molecules in an asymmetric unit, and ultracentrifugation data confirms that it forms a stable dimer in solution, consistent with the 1.9 Å-resolution structure. Our assays confirm that MsKSI accelerates the Kemp elimination of 5-nitrobenzoxazole (5NBI) with an optimal pH of 5.5. A 2.35 Å resolution crystal structure of the MsKSI-5NBI complex reveals that the substrate 5NBI is bound in the active pocket of the enzyme composed of hydrophobic residues. In addition, the Glu127 residue is proposed to play an important role as a general base in proton transfer and breaking weak O-N bonds to open the five-membered ring. This work provides a starting point for exploring the artificial modification of MsKSI using the natural enzyme as the backbone.

PubMed: 33992958
DOI: 10.1016/j.bbrc.2021.05.007

実験手法

X-RAY DIFFRACTION (2.35 Å)