- Engineering of CYP106A2 for steroid 9α- and 6β-hydroxylation
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CYP 106A2 from Bacillus megaterium ATCC 13368 has been described as a 15β-hydroxylase showing also minor 11α-, 9α- and 6β-hydroxylase activity for progesterone conversion. Previously, mutant proteins with a changed selectivity towards 11α-OH-progesterone have already been produced. The challenge of this work was to create mutant proteins with a higher regioselectivity towards hydroxylation at positions 9 and 6 of the steroid molecule. 9α-hydroxyprogesterone exhibits pharmaceutical importance, because it is a useful intermediate in the production of physiologically active substances which possess progestational activity. Sixteen mutant proteins were selected from a library containing mutated proteins created by a combination of site-directed and saturation mutagenesis of active site residues. Four mutant proteins out of these catalyzed the conversion of progesterone to 9α-OH-progesterone as a main product. For further optimization site-directed mutagenesis was performed. The introduction of seven mutations (D217V, A243V, A106T, F165L, T89N, T247V or T247W) into these four mutant proteins led to 28 new variants, which were also used for an in vivo conversion of progesterone. The best mutant protein, F165L/A395E/G397V, showed a ten-fold increase in the selectivity towards progesterone 9α-hydroxylation compared with the wild type CYP106A2. Also 6β-OH-progesterone is a pharmaceutically important compound, especially as intermediate for the production of drugs against breast cancer. For the rational design of mutant proteins with 6β-selectivity, docking of the 3D-structure of CYP106A2 with progesterone was performed. The introduction of three mutations (T247A, A243S, F173A) led to seven new mutant proteins. Clone A243S showed the greatest improvement in 6β-selectivity being more than ten-fold. Finally, an in vivo conversion of 11-deoxycorticosterone (DOC), testosterone and cortisol with the best five mutant proteins displaying 9α- or 6β-hydroxylation, respectively, of progesterone was performed to investigate whether the introduced mutations also effected the conversion of other substrates.
- Nikolaus, Julia,Nguyen, Kim Thoa,Virus, Cornelia,Riehm, Jan L.,Hutter, Michael,Bernhardt, Rita
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- Novel metabolites of dehydroepiandrosterone and progesterone obtained in Didymosphearia igniaria KCH 6670 culture
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Dehydroepiandrosterone (DHEA) (10) and its five derivatives: testosterone (1), androstenedione (2), 17α-methyltestosterone (6), progesterone (13) and pregnenolone (14) were subjected to microbial transformation by the filamentous fungus Didymosphaeria igniaria KCH 6670. The predominant metabolism of the incubated 5-ene steroids (10 and 14) occurred through 3β-hydroxy-steroid dehydrogenase/5,4-en isomerase pathways resulting in the generation of a 4-en-3-oxo system on ring-A. The transformations of C 19 steroids (1, 2, and 10) included a hydroxylation at 7α position, ketone-alcohol interconversion at C-17 and reduction of the double bond at C-4 and 3-keto group to the 3β-alcohol with 5α- stereochemistry at A/B ring. D. igniaria also carried out 6(7)-dehydrogenation and 6,7β-epoxidation during transformation of DHEA. Under these conditions transformation of DHEA (10) gave four products: 7α-hydroxyandrost-4-en-3, 17-dione (4), 17β-hydroxyandrost-4,6-dien-3-one (11), 17β- hydroxyandrost-6β-epoxy-4-en-3-one (12) and 3β,17β-dihydroxy- 5α-androstane (5). The compounds 11 and 12 are identified as DHEA metabolites for the first time. The transformation of C21 steroids (13 and 14) led to the mixture of mono- (mainly 11α- and 15β-) and dihydroxy- (7α,15β-; 14α,15β-; 11α,15β-; 11α,14α-) products. 7α,15β-Dihydroxypregnan-4-en-3,20- dione (18) and 14α,15β-dihydroxypregnan-4-en-3,20-dione (19) were found to be new compounds. The main product of transformation of 17α-methyltestosterone (6) was 12β-hydroxy-17α- methyltestosterone (7). The results of these transformations demonstrate the dependence of hydroxylation position on the structure of steroid nucleus.
- Janeczko, Tomasz,Swizdor, Alina,Dmochowska-Gladysz, Jadwiga,Bialonska, Agata,Ciunik, Zbigniew,Kostrzewa-Suslow, Edyta
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experimental part
p. 24 - 31
(2012/10/08)
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