Appl Environ Microbiol. 1994 May;60(5):1512-8. doi: 10.1128/aem.60.5.1512-1518.1994.

Role of neutral metabolites in microbial conversion of 3beta-acetoxy-19-hydroxycholest-5-ene into estrone.

Applied and environmental microbiology

K M Madyastha, V N Shankar

PMID: 16349252 PMCID: PMC201510 DOI: 10.1128/aem.60.5.1512-1518.1994

Abstract

Biotransformation of 3beta-acetoxy-19-hydroxycholest-5-ene (19-HCA, 6 g) by Moraxella sp. was studied. Estrone (712 mg) was the major metabolite formed. Minor metabolites identified were 5alpha-androst-1-en-19-ol-3,17-dione (33 mg), androst-4-en-19-ol-3,17-dione (58 mg), androst-4-en-9alpha,19-diol-3,17-dione (12 mg), and androstan-19-ol-3,17-dione (1 mg). Acidic metabolites were not formed. Time course experiments on the fermentation of 19-HCA indicated that androst-4-en-19-ol-3,17-dione was the major metabolite formed during the early stages of incubation. However, with continuing fermentation its level dropped, with a concomitant increase in estrone. Fermentation of 19-HCA in the presence of specific inhibitors or performing the fermentation for a shorter period (48 h) did not result in the formation of acidic metabolites. Resting-cell experiments carried out with 19-HCA (200 mg) in the presence of alpha,alpha'-bipyridyl led to the isolation of three additional metabolites, viz., cholestan-19-ol-3-one (2 mg), cholest-4-en-19-ol-3-one (10 mg), and cholest-5-en-3beta,19-diol (12 mg). Similar results were also obtained when n-propanol was used instead of alpha,alpha'-bipyridyl. Resting cells grown on 19-HCA readily converted both 5alpha-androst-1-en-19-ol-3,17-dione and androst-4-en-19-ol-3,17-dione into estrone. Partially purified 1,2-dehydrogenase from steroid-induced Moraxella cells transformed androst-4-en-19-ol-3,17-dione into estrone and formaldehyde in the presence of phenazine methosulfate, an artificial electron acceptor. These results suggest that the degradation of the hydrocarbon side chain of 19-HCA does not proceed via C(22) phenolic acid intermediates and complete removal of the C(17) side chain takes place prior to the aromatization of the A ring in estrone. The mode of degradation of the sterol side chain appears to be through the fission of the C(17)-C(20) bond. On the basis of these observations, a new pathway for the formation of estrone from 19-HCA in Moraxella sp. has been proposed.

References

1. J Steroid Biochem. 1983 Oct;19(4):1391-5 - PubMed
2. J Lipid Res. 1983 Nov;24(11):1500-11 - PubMed
3. J Steroid Biochem. 1985 Sep;23(3):327-32 - PubMed
4. J Biol Chem. 1962 Mar;237:699-702 - PubMed
5. J Bacteriol. 1960 Mar;79:426-34 - PubMed
6. J Am Chem Soc. 1967 Apr 12;89(8):1957-8 - PubMed
7. Adv Appl Microbiol. 1977;22:29-58 - PubMed
8. Xenobiotica. 1989 Feb;19(2):217-24 - PubMed
9. J Biol Chem. 1958 Oct;233(4):843-52 - PubMed
10. Biochemistry. 1968 Feb;7(2):796-807 - PubMed
11. J Am Chem Soc. 1967 Apr 12;89(8):1956-7 - PubMed
12. J Biol Chem. 1951 Nov;193(1):265-75 - PubMed

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