7ENY

Crystal structure of hydroxysteroid dehydrogenase from Escherichia coli

Summary for 7ENY

• Entry DOI: 10.2210/pdb7eny/pdb
• Descriptor: 7alpha-hydroxysteroid dehydrogenase (2 entities in total)
• Functional Keywords: ketolithocholic acid, alcohol dehydrogenase, hydroxysteroid dehydrogenase, ursodeoxycholic acid, hydrolase
• Biological source: Escherichia coli K-12
• Total number of polymer chains: 8
• Total formula weight: 242563.64

Authors

Kim, K.-H.,Lee, C.W.,Pardhe, D.P.,Hwang, J.,Do, H.,Lee, Y.M.,Lee, J.H.,Oh, T.-J. (deposition date: 2021-04-21, release date: 2021-07-14, Last modification date: 2023-11-29)

Primary citation

Kim, K.H.,Lee, C.W.,Pardhe, B.D.,Hwang, J.,Do, H.,Lee, Y.M.,Lee, J.H.,Oh, T.J.
Crystal structure of an apo 7 alpha-hydroxysteroid dehydrogenase reveals key structural changes induced by substrate and co-factor binding.
J.Steroid Biochem.Mol.Biol., 212:105945-105945, 2021

PubMed Abstract: 7α-Hydroxysteroid dehydrogenase (7α-HSDH) catalyzes the dehydrogenation of a hydroxyl group at the 7α position in steroid substrates using NAD or NADP as a co-factor. Although studies have determined the binary and ternary complex structures, detailed structural changes induced by ligand and co-factor binding remain unclear, because ligand-free structures are not yet available. Here, we present the crystal structure of apo 7α-HSDH from Escherichia coli (Eco-7α-HSDH) at 2.7 Å resolution. We found that the apo form undergoes substantial conformational changes in the β4-α4 loop, α7-α8 helices, and C-terminus loop among the four subunits comprising the tetramer. Furthermore, a comparison of the apo structure with the binary (NAD)-complex and ternary (NADH and 7-oxoglycochenodeoxycholic acid)-complex Eco-7α-HSDH structures revealed that only the ternary-complex structure has a fully closed conformation, whereas the binary-complex and apo structures have a semi-closed or open conformation. This open-to-closed transition forces several catalytically important residues (S146, Y159, and K163) into correct positions for catalysis. To confirm the catalytic activity, we used alcohol dehydrogenase for NAD regeneration to allow efficient conversion of chenodeoxycholic acid to 7-ketolithocholic acid by Eco-7α-HSDH. These findings demonstrate that apo Eco-7α-HSDH exhibits intrinsically flexible characteristics with an open conformation. This structural information provides novel insight into the 7α-HSDH reaction mechanism.

PubMed: 34171491
DOI: 10.1016/j.jsbmb.2021.105945

Experimental method

X-RAY DIFFRACTION (2.703 Å)