A Novel Testosterone Catabolic Pathway in Bacteria

Abstract

Forty years ago, Coulter and Talalay (A. W. Coulter and P. Talalay, J. Biol. Chem. 243:3238-3247, 1968) established the oxygenase-dependent pathway for the degradation of testosterone by aerobes. The oxic testosterone catabolic pathway involves several oxygen-dependent reactions and is not available for anaerobes. Since then, a variety of anaerobic bacteria have been described for the ability to degrade testosterone in the absence of oxygen. Here, a novel, oxygenase-independent testosterone catabolic pathway in such organisms is described. Steroidobacter denitrificans DSMZ18526 was shown to be capable of degrading testosterone in the absence of oxygen and was selected as the model organism in this study. In a previous investigation, we identified the initial intermediates involved in an anoxic testosterone catabolic pathway, most of which are identical to those of the oxic pathway demonstrated in Comamonas testosteroni. In this study, five additional intermediates of the anoxic pathway were identified. We demonstrated that subsequent steps of the anoxic pathway greatly differ from those of the established oxic pathway, which suggests that a novel pathway for testosterone catabolism is present. In the proposed anoxic pathway, a reduction reaction occurs at C-4 and C-5 of androsta-1,4-diene-3,17-dione, the last common intermediate of both the oxic and anoxic pathways. After that, a novel hydration reaction occurs and a hydroxyl group is thus introduced to the C-1␣ position of C 19 steroid substrates. To our knowledge, an enzymatic hydration reaction occurring at the A ring of steroid compounds has not been reported before.

Anoxic Androgen Degradation by the Denitrifying Bacterium Sterolibacterium denitrificans via the 2,3-seco Pathway

“…The chemicals used were of analytical grade and were purchased from Mallinckrodt Baker, Merck, or Sigma-Aldrich. 3,17-Dihydroxy-9,10-seco-androsta-1,3,5(10)-triene-9-one, 3-hydroxy-9,10-seco-androsta-1,3,5(10)-triene-9,17-dione, 1-testosterone, androst-1-en-3,17-dione, 17-hydroxy-1-oxo-2,3-seco-androstan-3-oic acid (2,3-SAOA), and 1,17-dioxo-2,3-seco-androstan-3-oic acid were produced as described elsewhere (39,47). Sterolibacterium denitrificans DSMZ 13999 was purchased from the Deutsche Sammlung für Mikroorganismen und Zellkulturen (DSMZ), Braunschweig, Germany.…”

Anaerobic and aerobic cleavage of the steroid core ring structure by Steroidobacter denitrificans

“…The denitrifying growth of S. denitrifi cans with testosterone and the preparation of cell extracts were performed as previously described ( 21 ). To determine the origins of the oxygen atoms at C-1 and/or C-3 of 17-hydroxy-androstan-1,3-dione and 17-hydroxy-1-oxo-2,3-seco-androstan-3-oic acid (2,3-SAOA), two in vitro assays were performed.…”

“…The structures of HPLC-purifi ed intermediates were determined using NMR spectroscopy. by using the 2,6-dimethylphenol photometric method as described elsewhere ( 21 ).…”

“…Recently, the initial reactions involved in the anaerobic metabolism of cholesterol and testosterone were reported (19)(20)(21), albeit the ring cleavage details of the anaerobic pathways are yet to be unraveled. In this study, we adopted a 13 C metabolomic approach to investigate the anaerobic degradation of testosterone using S. denitrifi cans as a model organism.…”

Substrate Uptake and Subcellular Compartmentation of Anoxic Cholesterol Catabolism in Sterolibacterium denitrificans

“…25-Hydroxycholest-4-en-3-one, 1-testosterone, androst-1-en-3,17-dione, 17-hydroxy-1-oxo-2,3-seco-androstan-3-oic acid (2, 3-SAOA), and 1,17-dioxo-2,3-seco-androstan-3-oic acid were produced according to previously determined methods (10,32,33). 26-Hydroxycholest-4-en-3-one (also named 27-hydroxy-4-cholesten-3-one, 99%) and cholest-4-en-3-one-26-oic acid (also named 3-oxo-4-cholestenoic acid, 99%) were obtained from Avanti Polar Lipids, and cholest-4-en-3-one-24-oic acid (also named 4-cholenic acid-3-one) and pregn-4-en-3-one-20-carboxylic acid (also named 4-pregnen-3-one-20␤-carboxylic acid) were purchased from Steraloids.…”