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Retroconversion of estrogens into androgens by bacteria via a cobalamin-mediated methylation.

ABSTRACT: Steroid estrogens modulate physiology and development of vertebrates. Conversion of C19 androgens into C18 estrogens is thought to be an irreversible reaction. Here, we report a denitrifying Denitratisoma sp. strain DHT3 capable of catabolizing estrogens or androgens anaerobically. Strain DHT3 genome contains a polycistronic gene cluster, emtABCD, differentially transcribed under estrogen-fed conditions and predicted to encode a cobalamin-dependent methyltransferase system conserved among estrogen-utilizing anaerobes; an emtA-disrupted DHT3 derivative could catabolize androgens but not estrogens. These data, along with the observed androgen production in estrogen-fed strain DHT3 cultures, suggested the occurrence of a cobalamin-dependent estrogen methylation to form androgens. Consistently, the estrogen conversion into androgens in strain DHT3 cell extracts requires methylcobalamin and is inhibited by propyl iodide, a specific inhibitor of cobalamin-dependent enzymes. The identification of the cobalamin-dependent estrogen methylation thus represents an unprecedented metabolic link between cobalamin and steroid metabolism and suggests that retroconversion of estrogens into androgens occurs in the biosphere.

SUBMITTER: Wang PH

PROVIDER: S-EPMC6983444 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Retroconversion of estrogens into androgens by bacteria via a cobalamin-mediated methylation.

Wang Po-Hsiang PH Chen Yi-Lung YL Wei Sean Ting-Shyang ST Wu Kan K Lee Tzong-Huei TH Wu Tien-Yu TY Chiang Yin-Ru YR

Proceedings of the National Academy of Sciences of the United States of America 20191217 3

Steroid estrogens modulate physiology and development of vertebrates. Conversion of C19 androgens into C18 estrogens is thought to be an irreversible reaction. Here, we report a denitrifying Denitratisoma sp. strain DHT3 capable of catabolizing estrogens or androgens anaerobically. Strain DHT3 genome contains a polycistronic gene cluster, emtABCD, differentially transcribed under estrogen-fed conditions and predicted to encode a cobalamin-dependent methyltrans ...[more]

PMID: 31848239

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Project description:Bacterial degradation of endocrine disrupting and carcinogenic estrogens is essential for their elimination from the environment. Recent studies of the denitrifying, estrogen-degrading Denitratisoma strain DHT3 revealed the conversion of estrogens to androgens by a putative cobalamin-dependent methyltransferase encoded by the emtABCD genes. The methyl donor and its continuous regeneration to initiate estradiol catabolism have remained unknown. Here, large-scale cultivation of the denitrifying bacterium Denitratisoma oestradiolicum with estrogen provided the biomass required for quantitative biochemical analyses. Soluble fractions of extracts from estradiol-grown cells catalyzed the S-adenosyl-l-methionine (SAM)- and Ti(III)-citrate-dependent conversion of 17?-estradiol/estrone to the respective androgens at 0.15?nmol min-1?mg-1 Kinetic studies of 17?-estradiol methylation and reverse 1-dehydrotestosterone demethylation reactions indicated that the exergonic methyl transfer from SAM to the putative cobalamin drives the endergonic methyl transfer from the methylcobalamin intermediate to the phenolic ring A. Based on a high-quality circular genome from D. oestradiolicum, proteogenomic analyses identified a 17?-estradiol-induced gene cluster comprising emtABCD genes together with genes involved in SAM regeneration via l-serine and l-methionine. Consistent with this finding, l-methionine/ATP or l-serine/ATP/tetrahydrofolate/l-homocysteine substituted for SAM as methyl donors, further confirmed by the incorporation of the 13C-methyl-group from 13C-l-methonine into methyl(III)cobalamine and the estrone methylation product androsta-1,4-diene-3-one. This work demonstrates that during bacterial estrogen catabolism, the C1 pool is channeled toward the initiating methyl transfer to ring A. The effective cellular SAM regeneration system may serve as a model for whole-cell SAM-dependent methylation reactions of biotechnological interest.IMPORTANCE Estrogens comprise a group of related hormones occurring in predominantly female vertebrates, with endocrine disrupting and carcinogenic potential. Microbial biodegradation of estrogens is essential for their elimination from surface waters and wastewater. Aerobic bacteria employ oxygenases for the initial cleavage of the aromatic ring A. In contrast, anaerobic degradation of estrogens is initiated by methyl transfer-dependent conversion into androgens involving a putative cobalamin-dependent methyltransferase system. The methyl donor for this unprecedented reaction and its stoichiometric regeneration have remained unknown. With the biomass obtained from large-scale fermentation of an estrogen-degrading denitrifying bacterium, we identified S-adenosyl-methionine (SAM) as the methyl donor for the cobalamin-mediated methyl transfer to estrogens. To continuously supply C1 units to initiate estrogen degradation, genes for SAM regeneration from estradiol-derived catabolites are highly upregulated. Data presented here shed light into biochemical processes involved in the globally important microbial degradation of estrogens.

Project description:BackgroundThe role of sex hormones on cellular function is unclear. Studies show androgens and estrogens are protective in the CNS, whereas other studies found no effects or damaging effects. Furthermore, sex differences have been observed in multiple oxidative stress-associated CNS disorders, such as Alzheimer's disease, depression, and Parkinson's disease. The goal of this study is to examine the relationship between sex hormones (i.e., androgens and estrogens) and oxidative stress on cell viability.MethodsN27 and PC12 neuronal and C6 glial phenotypic cell lines were used. N27 cells are female rat derived, whereas PC12 cells and C6 cells are male rat derived. These cells express estrogen receptors and the membrane-associated androgen receptor variant, AR45, but not the full-length androgen receptor. N27, PC12, and C6 cells were exposed to sex hormones either before or after an oxidative stressor to examine neuroprotective and neurotoxic properties, respectively. Estrogen receptor and androgen receptor inhibitors were used to determine the mechanisms mediating hormone-oxidative stress interactions on cell viability. Since the presence of AR45 in the human brain tissue was unknown, we examined the postmortem brain tissue from men and women for AR45 protein expression.ResultsNeither androgens nor estrogens were protective against subsequent oxidative stress insults in glial cells. However, these hormones exhibited neuroprotective properties in neuronal N27 and PC12 cells via the estrogen receptor. Interestingly, a window of opportunity exists for sex hormone neuroprotection, wherein temporary hormone deprivation blocked neuroprotection by sex hormones. However, if sex hormones are applied following an oxidative stressor, they exacerbated oxidative stress-induced cell loss in neuronal and glial cells.ConclusionsSex hormone action on cell viability is dependent on the cellular environment. In healthy neuronal cells, sex hormones are protective against oxidative stress insults via the estrogen receptor, regardless of sex chromosome complement (XX, XY). However, in unhealthy (e.g., high oxidative stress) cells, sex hormones exacerbated oxidative stress-induced cell loss, regardless of cell type or sex chromosome complement. The non-genomic AR45 receptor, which is present in humans, mediated androgen's damaging effects, but it is unknown which receptor mediated estrogen's damaging effects. These differential effects of sex hormones that are dependent on the cellular environment, receptor profile, and cell type may mediate the observed sex differences in oxidative stress-associated CNS disorders.

Project description:BackgroundAndrogen deficiency affects men in the adulthood, causing several harmful effects at the reproductive and behavioural levels. Since aromatase is an enzyme that catalyses the conversion of androgens to estrogens, and it is responsible for an adequate balance of both sex hormones in males and females, the administration of molecules acting as down modulators may contribute to restore an abnormal enzymatic activity. A prospective pilot study was carried out to investigate the effect of D-chiro-inositol, a putative aromatase down-modulator, on serum levels of testosterone, estradiol, estrone, dehydroepiandrosterone and epiandrosterone from a group of adult male volunteers. Glucose, insulin, follicle-stimulating hormone, luteinizing hormone, inhibin B, D-chiro-inositol and myo-inositol serum levels were also measured.ResultsMale volunteers were selected according to age and body mass index. Subjects with altered glycemia and/or hormonal status, due to advanced age or abnormal weight, were enrolled in the study. Each of the 10 volunteers enrolled took oral D-chiro-inositol (1 g/day) for 1 month. Serum assays of selected markers were performed at baseline (control) and after treatment. D-chiro-inositol administration was associated to reduced serum levels of estrone (- 85.0%) and estradiol (- 14.4%), and increased serum levels of testosterone (+ 23.4%) and dehydroepiandrosterone (+ 13.8%). In addition, epiandrosterone levels were higher (+39%) after treatment. On the other hand, follicle-stimulating hormone, luteinizing hormone and inhibin B did not change. A trend toward a decrease of glycemia, insulinemia and Homeostatic Model Assessment index was observed after D-chiro-inositol treatment, although differences did not reach statistical significance. D-chiro-inositol treatment did not cause any noticeable adverse effect.ConclusionsIncreased androgens and decreased estrogens seem to confirm that D-chiro-inositol acts as an aromatase down-modulator, but with a still unknown mechanism of action. This pilot study opens up new perspectives of research and therapeutic applications for D-chiro-inositol at different dosages and length of treatment. Authorization number 005/2020 released by the Local Ethics Committee of Alma Res Fertility Center, Rome.Trial registration numberNCT04615767 (registry: ClinicalTrials.gov) Date of registration: November 3, 2020.

Dataset Information

Retroconversion of estrogens into androgens by bacteria via a cobalamin-mediated methylation.

Publications

Retroconversion of estrogens into androgens by bacteria via a cobalamin-mediated methylation.

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