Degradation of the Acyl Side Chain of the Steroid Compound Cholate in Pseudomonas sp. Strain Chol1 Proceeds via an Aldehyde Intermediate
| Autor: | Johannes Holert, Vemparthan Suvekbala, Onur Yücel, Heiko M. Möller, Marc J.-F. Suter, Bodo Philipp, Žarko Kulić |
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| Rok vydání: | 2012 |
| Předmět: |
Stereochemistry
Coenzyme A medicine.medical_treatment Biology Microbiology Aldehyde Catalysis Gene Expression Regulation Enzymologic Steroid chemistry.chemical_compound Adenosine Triphosphate Pseudomonas medicine Side chain Molecular Biology Aldehyde-Lyases chemistry.chemical_classification Aldehydes Molecular Structure Aldolase A Articles Gene Expression Regulation Bacterial NAD Metabolic pathway chemistry Biochemistry ddc:540 biology.protein NAD+ kinase Cholates Oxidation-Reduction Adenosine triphosphate NADP |
| Zdroj: | Journal of Bacteriology. 195:585-595 |
| ISSN: | 0021-9193 |
| DOI: | 10.1128/jb.01961-12 |
| Popis: | Bacterial degradation of steroids is widespread, but the metabolic pathways have rarely been explored. Previous studies with Pseudomonas sp. strain Chol1 and the C24 steroid cholate have shown that cholate degradation proceeds via oxidation of the A ring, followed by cleavage of the C5 acyl side chain attached to C-17, with 7α,12β-dihydroxy-androsta-1,4-diene-3,17-dione (12β-DHADD) as the product. In this study, the pathway for degradation of the acyl side chain of cholate was investigated in vitro with cell extracts of strain Chol1. For this, intermediates of cholate degradation were produced with mutants of strain Chol1 and submitted to enzymatic assays containing coenzyme A (CoA), ATP, and NAD+ as cosubstrates. When the C24 steroid (22E)-7α,12α-dihydroxy-3-oxochola-1,4,22-triene-24-oate (DHOCTO) was used as the substrate, it was completely transformed to 12α-DHADD and 7α-hydroxy-androsta-1,4-diene-3,12,17-trione (HADT) as end products, indicating complete removal of the acyl side chain. The same products were formed with the C22 steroid 7α,12α-dihydroxy-3-oxopregna-1,4-diene-20-carboxylate (DHOPDC) as the substrate. The 12-keto compound HADT was transformed into 12β-DHADD in an NADPH-dependent reaction. When NAD+ was omitted from assays with DHOCTO, a new product, identified as 7α,12α-dihydroxy-3-oxopregna-1,4-diene-20S-carbaldehyde (DHOPDCA), was formed. This aldehyde was transformed to DHOPDC and DHOPDC-CoA in the presence of NAD+, CoA, and ATP. These results revealed that degradation of the C5 acyl side chain of cholate does not proceed via classical β-oxidation but via a free aldehyde that is oxidized to the corresponding acid. The reaction leading to the aldehyde is presumably catalyzed by an aldolase encoded by the gene skt, which was previously predicted to be a β-ketothiolase. |
| Databáze: | OpenAIRE |
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