6el3
From Proteopedia
Structure of Progesterone 5beta-Reductase from Arabidopsis thaliana in complex with NADP
Structural highlights
Function[VEP1_ARATH] Involved in vascular strand development. Catalyzes the stereospecific conversion of progesterone to 5-beta-pregnane-3,20-dione. Can use progesterone, testosterone, 21-acetyl cortexone, 2-cyclohexenone, but-1-en-3-one, ethyl acrylate, ethylmethacrylate, cortisone and canarigenone as substrates, lower activity with 3-methyl-2-cyclohexenone and 3,5,5-trimethyl-2-cyclohexenone as substrate, and no activity with canarigenin, canarigenin digitoxoside and pregnenolone. May be involved in the formation of 5-beta phytoecdysteroids.[1] [2] Publication Abstract from PubMedPRISEs (progesterone 5beta-reductase and/or iridoid synthase-like 1,4-enone reductases) are involved in cardenolide and iridoid biosynthesis. We here investigated a PRISE (rAtSt5betaR) from Arabidopsis thaliana, a plant producing neither cardenolides nor iridoids. The structure of rAtSt5betaR was elucidated with X-ray crystallography and compared to the known structures of PRISEs from Catharanthus roseus (rCrISY) and Digitalis lanata (rDlP5betaR). The three enzymes show a high degree of sequence and structure conservation in the active site. Amino acids previously considered to allow discrimination between progesterone 5beta-reductase and iridoid synthase were interchanged among rAtSt5betaR, rCrISY and rDlP5betaR applying site-directed mutagenesis. Structural homologous substitutions had different effects, and changes in progesterone 5beta-reductase and iridoid synthase activity were not correlated in all cases. Our results help to explain fortuitous emergence of metabolic pathways and product accumulation. The fact that PRISEs are found ubiquitously in spermatophytes insinuates that PRISEs might have a more general function in plant metabolism such as, for example, the detoxification of reactive carbonyl species. PRISEs (progesterone 5beta-reductase and/or iridoid synthase-like 1,4-enone reductases): Catalytic and substrate promiscuity allows for realization of multiple pathways in plant metabolism.,Schmidt K, Petersen J, Munkert J, Egerer-Sieber C, Hornig M, Muller YA, Kreis W Phytochemistry. 2018 Aug 29;156:9-19. doi: 10.1016/j.phytochem.2018.08.012. PMID:30172078[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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