title: The three-dimensional structure of Clostridium absonum 7α-hydroxysteroid dehydrogenase: new insights into the conserved arginines for NADP(H) recognition.
abstract: 7α-hydroxysteroid dehydrogenase (7α-HSDH) can catalyse the oxidation of C7 α-OH of the steroid nucleus in the bile acid metabolism. In the paper we determined the crystal structure of 7α-HSDH from Clostridium absonum (CA 7α-HSDH) complexed with taurochenodeoxycholic acid (TCDCA) and NADP(+) by X-ray diffraction, which, as a tetramer, possesses the typical α/β folding pattern. The four subunits of an asymmetric unit lie in the fact that there are the stable hydrophobic interactions between Q-axis-related subunits. Significantly, we captured an active state of the NADP(+), confirming that nicotinamide moiety of NADP(+) act as electron carrier in the dehydrogenation. On the basis of crystal structure analysis, site-directed mutagenesis and MD simulation, furthermore, we find that the guanidinium of Arg38 can form the stable cation-π interaction with the adenine ring of NADP(+), and the cation-π interaction and hydrogen bonds between Arg38 and NADP(+) have a significant anchor effect on the cofactor binding to CA 7α-HSDH.
authors.affiliation: Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, China.|Postdoctoral research station of biology, Chongqing University, Chongqing 400030, China.
authors.forename: Deshuai
authors.initials: D
authors.lastname: Lou
authors.affiliation: Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, China.
authors.forename: Bochu
authors.initials: B
authors.lastname: Wang
authors.affiliation: Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, China.|School of Biological &Chemical engineering, Chongqing University of Education, Chongqing 400067, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Tan
authors.affiliation: Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, China.
authors.forename: Liancai
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, China.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Cen
authors.affiliation: Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, China.
authors.forename: Qingzhi
authors.initials: Q
authors.lastname: Ji
authors.affiliation: Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
mesh_terms: D003013:Clostridium / Q000201:enzymology*; D018360:Crystallography, X-Ray; D006913:Hydroxysteroid Dehydrogenases / Q000737:chemistry* / Q000235:genetics; D056004:Molecular Dynamics Simulation; D016297:Mutagenesis, Site-Directed; D009249:NADP / Q000737:chemistry; D013655:Taurochenodeoxycholic Acid / Q000737:chemistry
chemical_list: D013655:Taurochenodeoxycholic Acid; D009249:NADP; D006913:Hydroxysteroid Dehydrogenases; C025376:7 alpha-hydroxysteroid dehydrogenase