title: Crystal structure of perakine reductase, founding member of a novel aldo-keto reductase (AKR) subfamily that undergoes unique conformational changes during NADPH binding.
abstract: Perakine reductase (PR) catalyzes the NADPH-dependent reduction of the aldehyde perakine to yield the alcohol raucaffrinoline in the biosynthetic pathway of ajmaline in Rauvolfia, a key step in indole alkaloid biosynthesis. Sequence alignment shows that PR is the founder of the new AKR13D subfamily and is designated AKR13D1. The x-ray structure of methylated His(6)-PR was solved to 2.31 Å. However, the active site of PR was blocked by the connected parts of the neighbor symmetric molecule in the crystal. To break the interactions and obtain the enzyme-ligand complexes, the A213W mutant was generated. The atomic structure of His(6)-PR-A213W complex with NADPH was determined at 1.77 Å. Overall, PR folds in an unusual α(8)/β(6) barrel that has not been observed in any other AKR protein to date. NADPH binds in an extended pocket, but the nicotinamide riboside moiety is disordered. Upon NADPH binding, dramatic conformational changes and movements were observed: two additional β-strands in the C terminus become ordered to form one α-helix, and a movement of up to 24 Å occurs. This conformational change creates a large space that allows the binding of substrates of variable size for PR and enhances the enzyme activity; as a result cooperative kinetics are observed as NADPH is varied. As the founding member of the new AKR13D subfamily, PR also provides a structural template and model of cofactor binding for the AKR13 family.
authors.affiliation: Institute of Materia Medica, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Lianli
authors.initials: L
authors.lastname: Sun
authors.forename: Yixin
authors.initials: Y
authors.lastname: Chen
authors.forename: Chitra
authors.initials: C
authors.lastname: Rajendran
authors.forename: Uwe
authors.initials: U
authors.lastname: Mueller
authors.forename: Santosh
authors.initials: S
authors.lastname: Panjikar
authors.forename: Meitian
authors.initials: M
authors.lastname: Wang
authors.forename: Rebekka
authors.initials: R
authors.lastname: Mindnich
authors.forename: Cindy
authors.initials: C
authors.lastname: Rosenthal
authors.forename: Trevor M
authors.initials: TM
authors.lastname: Penning
authors.forename: Joachim
authors.initials: J
authors.lastname: Stöckigt
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D019143:Evolution, Molecular; D008745:Methylation; D008958:Models, Molecular; D009249:NADP / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation / Q000187:drug effects; D017433:Protein Structure, Secondary; D011926:Rauwolfia / Q000201:enzymology; D016415:Sequence Alignment
chemical_list: D009249:NADP; D000429:Alcohol Oxidoreductases; C530961:perakine reductase, Rauvolfia serpentina