Identification and characterization of a 20β-HSDH from the anaerobic gut bacterium Butyricicoccus desmolans ATCC 43058

Abstract

Members of the gastrointestinal microbiota are known to convert glucocorticoids to androstanes, which are subsequently converted to potent androgens by other members of the gut microbiota or host tissues. Butyricicoccus desmolans and Clostridium cadaveris have previously been reported for steroid-17,20-desmolase and 20β-hydroxysteroid dehydrogenase (HSDH) activities that are responsible for androstane formation from cortisol; however, the genes encoding these enzymes have yet to be reported. In this work, we identified and located a gene encoding 20β-HSDH in both B. desmolans and C. cadaveris. The 20β-HSDH of B. desmolans was heterologously overexpressed and purified from Escherichia coli. The enzyme was determined to be a homotetramer with subunit molecular mass of 33.8 ± 3.7 kDa. The r20β-HSDH displayed pH optimum in the reductive direction at pH 9.0 and in the oxidative direction at pH 7.0–7.5 with (20β-dihydro)cortisol and NAD(H) as substrates. Cortisol is the preferred substrate with Km, 0.80 ± 0.06 μM; Vmax, 30.36 ± 1.97 μmol·min−1; Kcat, 607 ± 39 μmol·μM−1·min−1; Kcat/Km, 760 ± 7.67. Phylogenetic analysis of the 20β-HSDH from B. desmolans suggested that the 20β-HSDH is found in several Bifidobacterium spp., one of which was shown to express 20β-HSDH activity. Notably, we also identified a novel steroid-17,20-desmolase-elaborating bacterium, Propionimicrobium lymphophilum, a normal inhabitant of the urinary tract.

Systematic mapping of drug metabolism by the human gut microbiome

“…3) . While C20 reduction was previously reported for hydrocortisone 31,32 , neither deacetylation nor C20 reduction were reported for hydrocortisone acetate. For capecitabine, we show that MDM results in complete deglycosylation, again, a modification never reported for this drug ( Fig.…”

“…4b ). None of the tested strains performed C20 reduction of hydrocortisone, suggesting that it is performed by a yet unidentified member(s) of the HD-1 microbiome (only two gut isolates were previously shown to perform C20 reduction on hydrocortisone: Clostridium scindens and Butyricicoccus desmolans ) 31,32 .…”

The desA and desB genes from Clostridium scindens ATCC 35704 encode steroid-17,20-desmolase

“…Prostate tissue contains 11β-hydroxyandrogens despite inhibition of host enzymes involved in synthesizing androgens (chemical castration) [27,28]. The role of 11β-OHAD formation by the gut microbiota in androgen accumulation in the prostate is unknown; however, we discovered that bacteria isolated from urine also express the bacterial steroid-17,20-desmolase pathway [11], and the majority of cortisol excretion from the body is via the urine [24,25]. Of note, we recently reported identification of the steroid-17,20-desmolase gene cluster in the genomes of urinary bacterial isolates and confirmed steroid-17,20-desmolase activity in an isolate of Propionimicrobium lymphophylum [11].…”

“…The role of 11β-OHAD formation by the gut microbiota in androgen accumulation in the prostate is unknown; however, we discovered that bacteria isolated from urine also express the bacterial steroid-17,20-desmolase pathway [11], and the majority of cortisol excretion from the body is via the urine [24,25]. Of note, we recently reported identification of the steroid-17,20-desmolase gene cluster in the genomes of urinary bacterial isolates and confirmed steroid-17,20-desmolase activity in an isolate of Propionimicrobium lymphophylum [11]. Verification that desA and desB genes encode steroid-17,20-desmolase is an important step towards the application of nucleic acidbased approaches such as quantitative polymerase chain, and metagenomic sequencing in determining whether correlations exist between levels/expression of desAB and host phenotypes and disease states.…”

The Cancer Microbiome: Distinguishing Direct and Indirect Effects Requires a Systemic View

“…Other bacteria in the gut metabolize estrogen, potentially altering the risk of postmenopausal estrogen receptorpositive breast cancer, even though the breast is far from the gut [9,10]. In men, microbes can generate 11-oxyandrogens from host glucocorticoids in the gut and urinary tract, which may contribute to prostate cancer [11][12][13].…”