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Project description:The cyp125 gene of Rhodococcus jostii RHA1 was previously found to be highly upregulated during growth on cholesterol and the orthologue in Mycobacterium tuberculosis (rv3545c) has been implicated in pathogenesis. Here we show that cyp125 is essential for R. jostii RHA1 to grow on 3-hydroxysterols such as cholesterol, but not on 3-oxo sterol derivatives, and that CYP125 performs an obligate first step in cholesterol degradation. The involvement of cyp125 in sterol side-chain degradation was confirmed by disrupting the homologous gene in Rhodococcus rhodochrous RG32, a strain that selectively degrades the cholesterol side-chain. The RG32 Omega cyp125 mutant failed to transform the side-chain of cholesterol, but degraded that of 5-cholestene-26-oic acid-3beta-ol, a cholesterol catabolite. Spectral analysis revealed that while purified ferric CYP125(RHA1) was < 10% in the low-spin state, cholesterol (K(D)(app) = 0.20 +/- 0.08 microM), 5 alpha-cholestanol (K(D)(app) = 0.15 +/- 0.03 microM) and 4-cholestene-3-one (K(D)(app) = 0.20 +/- 0.03 microM) further reduced the low spin character of the haem iron consistent with substrate binding. Our data indicate that CYP125 is involved in steroid C26-carboxylic acid formation, catalysing the oxidation of C26 either to the corresponding carboxylic acid or to an intermediate state.
| S-EPMC5218833 | biostudies-literature
Project description:Canine hypoadrenocorticism likely arises from immune-mediated destruction of adrenocortical tissue, leading to glucocorticoid and mineralocorticoid deficiency. In humans with autoimmune Addison's disease (AAD) or autoimmune polyendocrine syndrome (APS), circulating autoantibodies have been demonstrated against enzymes associated with adrenal steroid synthesis. The current study investigates autoantibodies against steroid synthesis enzymes in dogs with spontaneous hypoadrenocorticism. Coding regions of canine CYP21A2 (21-hydroxylase; 21-OH), CYP17A1 (17-hydroxylase; 17-OH), CYP11A1 (P450 side-chain cleavage enzyme; P450scc) and HSD3B2 (3? hydroxysteroid dehydrogenase; 3?HSD) were amplified, cloned and expressed as 35S-methionine radiolabelled recombinant protein. In a pilot study, serum samples from 20 dogs with hypoadrenocorticism and four unaffected control dogs were screened by radio-immunoprecipitation assay. There was no evidence of reactivity against 21-OH, 17-OH or 3?HSD, but five dogs with hypoadrenocorticism showed immunoreactivity to P450scc compared with controls. Serum samples were subsequently obtained from 213 dogs diagnosed with hypoadrenocorticism and 110 dogs from a hospital control population. Thirty control dogs were randomly selected to establish a threshold for antibody positivity (mean + 3 × standard deviation). Dogs with hypoadrenocorticism were more likely to be P450scc autoantibody positive than hospital controls (24% vs. 1.2%, respectively; p = 0.0016). Sex was significantly associated with the presence of P450scc autoantibodies in the case population, with 30% of females testing positive compared with 17% of males (p = 0.037). Significant associations with breed (p = 0.015) and DLA-type (DQA1*006:01 allele; p = 0.017) were also found. This cross-sectional study indicates that P450scc autoantibodies are present in a proportion of dogs affected with hypoadrenocorticism.
| S-EPMC4664467 | biostudies-literature
Project description:Physiological plasticity in a polluted system: A case of an uncultured bacterium and its cypome
| PRJEB38781 | ENA
Project description:The enzyme cytochrome P450 11A1 cleaves the C20-C22 carbon-carbon bond of cholesterol to form pregnenolone, the first 21-carbon precursor of all steroid hormones. Various reaction mechanisms are possible for the carbon-carbon bond cleavage step of P450 11A1, and most current proposals involve the oxoferryl active species, Compound I (FeO(3+)). Compound I can either (i) abstract an O-H hydrogen atom or (ii) be attacked by a nucleophilic hydroxy group of its substrate, 20R,22R-dihydroxycholesterol. The mechanism of this carbon-carbon bond cleavage step was tested using (18)O-labeled molecular oxygen and purified P450 11A1. P450 11A1 was incubated with 20R,22R-dihydroxycholesterol in the presence of molecular oxygen ((18)O2), and coupled assays were used to trap the labile (18)O atoms in the enzymatic products (i.e., isocaproaldehyde and pregnenolone). The resulting products were derivatized and the (18)O content was analyzed by high-resolution mass spectrometry. P450 11A1 showed no incorporation of an (18)O atom into either of its carbon-carbon bond cleavage products, pregnenolone and isocaproaldehyde . The positive control experiments established retention of the carbonyl oxygens in the enzymatic products during the trapping and derivatization processes. These results reveal a mechanism involving an electrophilic Compound I species that reacts with nucleophilic hydroxy groups in the 20R,22R-dihydroxycholesterol intermediate of the P450 11A1 reaction to produce the key steroid pregnenolone.
| S-EPMC5289895 | biostudies-literature
Project description:Cytochrome P450 monooxygenases play a prominent role in the biosynthesis of the diterpenoid anticancer drug Taxol, as they appear to constitute about half of the 19 enzymatic steps of the pathway in yew (Taxus) species. A combination of classical biochemical and molecular methods, including cell-free enzyme studies and differential-display of mRNA-reverse transcription polymerase chain reaction (RT-PCR) combined with a homology-based searching and random sequencing of a cDNA library from induced T. cuspidata cells, led to the discovery of six novel cytochrome P450 taxoid (taxane diterpenoid) hydroxylases. These genes show unusually high sequence similarity with each other (>70%) but low similarity (<30%) to, and significant evolutionary distance from, other plant P450s. Despite their high similarity, functional analysis of these hydroxylases demonstrated distinctive substrate specificities responsible for an early bifurcation in the biosynthetic pathway after the initial hydroxylation of the taxane core at C5, leading into a biosynthetic network of competing, but interconnected, branches. The use of surrogate substrates, in cases where the predicted taxoid precursors were not available, led to the discovery of two core oxygenases, the 2?- and the 7?-hydroxylase. This general approach could accelerate the functional analysis of candidate cDNAs from the extant family of P450 genes to identify the remaining oxygenation steps of this complex pathway.
| S-EPMC2901147 | biostudies-literature
Project description:Mycophenolic acid (MPA, 1) and its derivatives are first-line immunosuppressants used in organ transplantation and for treating autoimmune diseases. Despite chemical synthetic achievements, the biosynthetic formation of a seven-carbon carboxylic acid pharmacophore side chain of 1, especially the processes involving the cleavage of the prenyl side chain between DHMP (4) and DMMPA (5), remains unknown. In this work, we identified a membrane-bound prenyltransferase, PgMpaA, that transfers FPP to 4 to yield FDHMP (6). Compound 6 undergoes the first cleavage step via a new globin-like enzyme PgMpaB to form a cryptic intermediate 12. Heterologous expression of PgMpa genes in Aspergillus nidulans demonstrates that the second cleavage step (from 12 to 5) of 1 is a PgMpa cluster-independent process in vivo. Our results, especially the discovery of the broad tolerance of substrates recognized by PgMpaB, set up a strategy for the formation of "pseudo-isopentenyl" natural products using fungal globin-like enzymes.
| S-EPMC6900556 | biostudies-literature
Project description:Objective:CYP11A1 mutations cause P450 side-chain cleavage (scc) deficiency, a rare form of congenital adrenal hyperplasia with a wide clinical spectrum. We detail the phenotype and evolution in a male sibship identified by HaloPlex targeted capture array. Family study:The youngest of three brothers from a non-consanguineous Scottish family presented with hyperpigmentation at 3.7 years. Investigation showed grossly impaired glucocorticoid function with ACTH elevation, moderately impaired mineralocorticoid function, and normal external genitalia. The older brothers were found to be pigmented also, with glucocorticoid impairment but normal electrolytes. Linkage studies in 2002 showed that all three brothers had inherited the same critical regions of the maternal X chromosome suggesting an X-linked disorder, but analysis of NR0B1 (DAX-1, adrenal hypoplasia) and ABCD1 (adrenoleukodystrophy) were negative. In 2016, next-generation sequencing revealed compound heterozygosity for the rs6161 variant in CYP11A1 (c.940G>A, p.Glu314Lys), together with a severely disruptive frameshift mutation (c.790_802del, K264Lfs*5). The brothers were stable on hydrocortisone and fludrocortisone replacement, testicular volumes (15-20 mL), and serum testosterone levels (24.7, 33.3, and 27.2 nmol/L) were normal, but FSH (41.2 µ/L) was elevated in the proband. The latter had undergone left orchidectomy for suspected malignancy at the age of 25 years and was attending a fertility clinic for oligospermia. Initial histology was reported as showing nodular Leydig cell hyperplasia. However, histological review using CD56 staining confirmed testicular adrenal rest cell tumour (TART). Conclusion:This kinship with partial P450scc deficiency demonstrates the importance of precise diagnosis in primary adrenal insufficiency to ensure appropriate counselling and management, particularly of TART.
| S-EPMC7087497 | biostudies-literature
Project description:Pradimicins A-C (1-3) are a group of antifungal and antiviral polyketides from Actinomadura hibisca. The sugar moieties in pradimicins are required for their biological activities. Consequently, the 5-OH that is used for glycosylation plays a critical role in pradimicin biosynthesis. A cytochrome P450 monooxygenase gene, pdmJ, was amplified from the genomic DNA of A. hibisca and expressed in Escherichia coli BL21(DE3). PdmJ introduced a hydroxyl group to G-2A (4), a key pradimicin biosynthetic intermediate, at C-5 to form JX134 (5). A d-Ala-containing pradimicin analog, JX137a (6) was tested as an alternative substrate, but no product was detected by LC-MS, indicating that PdmJ has strict substrate specificity. Kinetic studies revealed a typical substrate inhibition of PdmJ activity. The optimal substrate concentration for the highest velocity is 115?M under the test conditions. Moreover, the conversion rate of 4 to 5 was reduced by the presence of 6, likely due to competitive inhibition. Coexpression of PdmJ and a glucose 1-dehydrogenase in E. coli BL21(DE3) provides an efficient method to produce the important intermediate 5 from 4.
| S-EPMC3248948 | biostudies-literature
Project description:Resistance to agricultural fungicides in the field has created a need for discovering fungicides with new modes of action. DNA microarrays, because they provide information on expression of many genes simultaneously, could help to identify the modes of action. To begin an expression pattern database for agricultural fungicides, transcriptional patterns of Saccharomyces cerevisiae strain S288C genes were analysed following 2-h treatments with I50 concentrations of ergosterol biosynthesis inhibitors commonly used against plant pathogenic fungi. Eight fungicides, representing three classes of ergosterol biosynthesis inhibitors, were tested. To compare gene expression in response to a fungicide with a completely different mode of action, a putative methionine biosynthesis inhibitor (MBI) was also tested. Expression patterns of ergosterol biosynthetic genes supported the roles of Class I and Class II inhibitors in affecting ergosterol biosynthesis, confirmed that the putative MBI did not affect ergosterol biosynthesis, and strongly suggested that in yeast, the Class III inhibitor did not affect ergosterol biosynthesis. The MBI affected transcription of three genes involved in methionine metabolism, whereas there were essentially no effects of ergosterol synthesis inhibitors on methionine metabolism genes. There were no consistent patterns in other up- or downregulated genes between fungicides. These results suggest that inspection of gene response patterns within a given pathway may serve as a useful first step in identifying possible modes of action of fungicides. agricultural sterol biosynthesis inhibitor fungicides. Keywords = agriculture Keywords = ergosterol Keywords = methionine Keywords = fungicide Keywords = Saccharomyces cerevisiae S288C Keywords = biosynthesis
2010-06-10 | E-GEOD-2412 | biostudies-arrayexpress
Project description:Resistance to agricultural fungicides in the field has created a need for discovering fungicides with new modes of action. DNA microarrays, because they provide information on expression of many genes simultaneously, could help to identify the modes of action. To begin an expression pattern database for agricultural fungicides, transcriptional patterns of Saccharomyces cerevisiae strain S288C genes were analysed following 2-h treatments with I50 concentrations of ergosterol biosynthesis inhibitors commonly used against plant pathogenic fungi. Eight fungicides, representing three classes of ergosterol biosynthesis inhibitors, were tested. To compare gene expression in response to a fungicide with a completely different mode of action, a putative methionine biosynthesis inhibitor (MBI) was also tested. Expression patterns of ergosterol biosynthetic genes supported the roles of Class I and Class II inhibitors in affecting ergosterol biosynthesis, confirmed that the putative MBI did not affect ergosterol biosynthesis, and strongly suggested that in yeast, the Class III inhibitor did not affect ergosterol biosynthesis. The MBI affected transcription of three genes involved in methionine metabolism, whereas there were essentially no effects of ergosterol synthesis inhibitors on methionine metabolism genes. There were no consistent patterns in other up- or downregulated genes between fungicides. These results suggest that inspection of gene response patterns within a given pathway may serve as a useful first step in identifying possible modes of action of fungicides. agricultural sterol biosynthesis inhibitor fungicides. Keywords = agriculture Keywords = ergosterol Keywords = methionine Keywords = fungicide Keywords = Saccharomyces cerevisiae S288C Keywords = biosynthesis
2005-05-01 | GSE2412 | GEO