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Bodo Philipp - One of the best experts on this subject based on the ideXlab platform.
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an unexplored pathway for degradation of Cholate requires a 7α hydroxysteroid dehydratase and contributes to a broad metabolic repertoire for the utilization of bile salts in novosphingobium sp strain chol11
Environmental Microbiology, 2016Co-Authors: Onur Yucel, Steffen L Drees, Nina Jagmann, Thomas Patschkowski, Bodo PhilippAbstract:Bile salts such as Cholate are surface-active steroid compounds with functions for digestion and signaling in vertebrates. Upon excretion into soil and water bile salts are an electron- and carbon-rich growth substrate for environmental bacteria. Degradation of bile salts proceeds via intermediates with a 3-keto-Δ1,4-diene structure of the steroid skeleton as shown for e.g. Pseudomonas spp. Recently, we isolated bacteria degrading Cholate via intermediates with a 3-keto-7-deoxy-Δ4,6-structure of the steroid skeleton suggesting the existence of a second pathway for Cholate degradation. This potential new pathway was investigated with Novosphingobium sp. strain Chol11. A 7α-hydroxysteroid dehydratase encoded by hsh2 was identified, which was required for the formation of 3-keto-7-deoxy-Δ4,6-metabolites. A hsh2 deletion mutant could still grow with Cholate but showed impaired growth. Cholate degradation of this mutant proceeded via 3-keto-Δ1,4-diene metabolites. Heterologous expression of Hsh2 in the bile salt-degrading Pseudomonas sp. strain Chol1 led to formation of a dead-end steroid with a 3-keto-7-deoxy-Δ4,6-diene structure. Hsh2 is the first steroid dehydratase with an important function in a metabolic pathway of bacteria that use bile salts as growth substrates. This pathway contributes to a broad metabolic repertoire of Novosphingobium strain Chol11 that may be advantageous in competition with other bile salt-degrading bacteria. This article is protected by copyright. All rights reserved.
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evidence of distinct pathways for bacterial degradation of the steroid compound Cholate suggests the potential for metabolic interactions by interspecies cross feeding
Environmental Microbiology, 2014Co-Authors: Johannes Holert, Onur Yucel, Vemparthan Suvekbala, žarko Kulic, Heiko M Moller, Bodo PhilippAbstract:Summary The distribution and the metabolic pathways of bacteria degrading steroid compounds released by eukaryotic organisms were investigated using the bile salt Cholate as model substrate. Cholate-degrading bacteria could be readily isolated from freshwater environments. All isolated strains transiently released steroid degradation intermediates into culture supernatants before their further degradation. Cholate degradation could be initiated via two different reaction sequences. Most strains degraded Cholate via a reaction sequence known from the model organism Pseudomonas sp. strain Chol1 releasing intermediates with a 3-keto-Δ1,4-diene structure of the steroid skeleton. The actinobacterium Dietzia sp. strain Chol2 degraded Cholate via a different and yet unexplored reaction sequence releasing intermediates with a 3-keto-Δ4,6-diene-7-deoxy structure of the steroid skeleton such as 3,12-dioxo-4,6-choldienoic acid (DOCDA). Using DOCDA as substrate, two Alphaproteobacteria, strains Chol10–11, were isolated that produced the same Cholate degradation intermediates as strain Chol2. With DOCDA as substrate for Pseudomonas sp. strain Chol1 only the side chain was degraded while the ring system was transformed into novel steroid compounds accumulating as dead-end metabolites. These metabolites could be degraded by the DOCDA-producing strains Chol10–11. These results indicate that bacteria with potentially different pathways for Cholate degradation coexist in natural habitats and may interact via interspecies cross-feeding.
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identification of a thiolase gene essential for β oxidation of the acyl side chain of the steroid compound Cholate in pseudomonas sp strain chol1
Fems Microbiology Letters, 2011Co-Authors: Antoinette Birkenmaier, Heiko M Moller, Bodo PhilippAbstract:Bile salts such as Cholate are steroid compounds occurring ubiquitously in the environment through excretion by animals. Cholate degradation by Pseudomonas sp. strain Chol1 is initiated by A-ring oxidation and β-oxidation of the acyl side chain. A transposon mutant of strain Chol1 was isolated that could not grow with Cholate, but transformed it into several steroid compounds accumulating in culture supernatants. The main product was identified as (22E)-7α,12α-dihydroxy-3-oxochola-1,4,22-triene-24-oate (DHOCTO). A further compound was identified as 7α,12α,22-trihydroxy-3-oxochola-1,4-diene-24-oate (THOCDO). The structures of DHOCTO and THOCDO indicate that they are intermediates of the β-oxidation of the acyl side chain. The interrupted gene was named skt and had similarities to the 3-ketoacyl-CoA thiolase domain of the eukaryotic sterol carrier protein SCP-x. An skt mutant grew with intermediates of Cholate degradation, from which the acyl side chain had been partly or completely removed. Growth with Cholate was restored by an intact skt copy on a plasmid. These results strongly suggest that skt encodes a β-ketothiolase responsible for the cleavage of acetyl-CoA from the acyl side chain of Cholate. Sequence comparisons revealed that other steroid-degrading bacteria such as Comamonas testosteroni contain genes encoding proteins very similar to Skt, suggesting a widespread role of this enzyme in bacterial steroid degradation.
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degradation of and sensitivity to Cholate in pseudomonas sp strain chol1
Archives of Microbiology, 2006Co-Authors: Bodo Philipp, Henrike Erdbrink, Marc J F Suter, Bernhard SchinkAbstract:A facultative anaerobic bacterium, Pseudomonas sp. strain Chol1, degrading Cholate and other bile acids was isolated from soil. We investigated how strain Chol1 grew with Cholate and whether growth was affected by the toxicity of this compound. Under anoxic conditions with nitrate as electron acceptor, strain Chol1 grew by transformation of Cholate to 7,12-dihydroxy-1,4-androstadiene-3,17-dione (DHADD) as end product. Under oxic conditions, strain Chol1 grew by transformation of Cholate to 3,7,12-trihydroxy-9,10-seco-1,3,5(10)-androstatriene-9,17-dione (THSATD), which accumulated in the culture supernatant before its further oxidation to CO2. Strain Chol1 converted DHADD into THSATD by an oxygenase-dependent reaction. Addition of Cholate (≥10 mM) to cell suspensions of strain Chol1 caused a decrease of optical density and viable counts but aerobic growth with these toxic Cholate concentrations was possible. Addition of CCCP or EDTA strongly increased the sensitivity of the cells to 10 mM Cholate. EDTA also increased the sensitivity of the cells to DHADD and THSATD (≤1.7 mM). The toxicity of Cholate and its degradation intermediates with a steroid structure indicates that strain Chol1 requires a strategy to minimize these toxic effects during growth with Cholate. Apparently, the proton motive force and the outer membrane are necessary for protection against these toxic effects.
William W Mohn - One of the best experts on this subject based on the ideXlab platform.
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rhodococcus jostii porin a rjpa functions in Cholate uptake
Applied and Environmental Microbiology, 2013Co-Authors: Vijayakumar Somalinga, William W MohnAbstract:RjpA in Rhodococcus jostii is the ortholog of a channel-forming porin, MspA. Deletion of rjpA delayed growth of R. jostii on Cholate but not on cholesterol. Eventual growth on Cholate involved increased expression of other porins, namely, RjpB, RjpC, and RjpD. Porins appear essential for the uptake of bile acids by mycolic acid bacteria.
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gene cluster encoding Cholate catabolism in rhodococcus spp
Journal of Bacteriology, 2012Co-Authors: William W Mohn, Maarten Hotse Wilbrink, Israel Casabon, Gordon R Stewart, Robert Van Der Geize, Lindsay D EltisAbstract:Bile acids are highly abundant steroids with important functions in vertebrate digestion. Their catabolism by bacteria is an important component of the carbon cycle, contributes to gut ecology, and has potential commercial applications. We found that Rhodococcus jostii RHA1 grows well on Cholate, as well as on its conjugates, tauroCholate and glycoCholate. The transcriptome of RHA1 growing on Cholate revealed 39 genes upregulated on Cholate, occurring in a single gene cluster. Reverse transcriptase quantitative PCR confirmed that selected genes in the cluster were upregulated 10-fold on Cholate versus on cholesterol. One of these genes, kshA3, encoding a putative 3-ketosteroid-9α-hydroxylase, was deleted and found essential for growth on Cholate. Two coenzyme A (CoA) synthetases encoded in the cluster, CasG and CasI, were heterologously expressed. CasG was shown to transform Cholate to cholyl-CoA, thus initiating side chain degradation. CasI was shown to form CoA derivatives of steroids with isopropanoyl side chains, likely occurring as degradation intermediates. Orthologous gene clusters were identified in all available Rhodococcus genomes, as well as that of Thermomonospora curvata. Moreover, Rhodococcus equi 103S, Rhodococcus ruber Chol-4 and Rhodococcus erythropolis SQ1 each grew on Cholate. In contrast, several mycolic acid bacteria lacking the gene cluster were unable to grow on Cholate. Our results demonstrate that the above-mentioned gene cluster encodes Cholate catabolism and is distinct from a more widely occurring gene cluster encoding cholesterol catabolism.
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two transporters essential for reassimilation of novel Cholate metabolites by rhodococcus jostii rha1
Journal of Bacteriology, 2012Co-Authors: Kendra Swain, Lindsay D Eltis, Israel Casabon, William W MohnAbstract:The bacterial uptake of steroids and their metabolites remains poorly understood. We investigated two transporters associated with Cholate catabolism in Rhodococcus jostii RHA1. Reverse transcriptase quantitative-PCR indicated that an ATP-binding cassette (ABC) transporter and a major facilitator superfamily (MFS) transporter were upregulated 16.7- and 174-fold, respectively, during the exponential phase of growth on Cholate compared to growth on pyruvate. Gene knockout analysis established that these transporters are required for the reassimilation of distinct metabolites that accumulate during growth on Cholate. The ABC transporter, encoded by camABCD, was essential for uptake of 1β(2′-propanoate)-3aα-H-4α(3″(R)-hydroxy-3″-propanoate)-7aβ-methylhexahydro-5-indanone and a desaturated analog. The MFS transporter, encoded by camM, was essential for uptake of 3,7(R),12(S)-trihydroxy-9-oxo-9,10-seco-23,24-bisnorchola-1,3,5(10)-trien-22-oate. These metabolites differ from Cholate metabolites reported to be excreted by proteobacteria in that they retain an isopropanoyl side chain at C-17. The uptake of these metabolites was necessary for maximal growth on Cholate: a ΔcamB mutant lacking the permease component of the ABC transporter and a ΔcamM mutant lacking the MFS transporter grew to 74% and 77%, respectively, of the yield of the wild type. This study demonstrates for the first time the requirement for specific transporters for uptake of Cholate metabolites and highlights the importance and complexity of transport processes associated with bacterial steroid catabolism.
Heiko M Moller - One of the best experts on this subject based on the ideXlab platform.
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evidence of distinct pathways for bacterial degradation of the steroid compound Cholate suggests the potential for metabolic interactions by interspecies cross feeding
Environmental Microbiology, 2014Co-Authors: Johannes Holert, Onur Yucel, Vemparthan Suvekbala, žarko Kulic, Heiko M Moller, Bodo PhilippAbstract:Summary The distribution and the metabolic pathways of bacteria degrading steroid compounds released by eukaryotic organisms were investigated using the bile salt Cholate as model substrate. Cholate-degrading bacteria could be readily isolated from freshwater environments. All isolated strains transiently released steroid degradation intermediates into culture supernatants before their further degradation. Cholate degradation could be initiated via two different reaction sequences. Most strains degraded Cholate via a reaction sequence known from the model organism Pseudomonas sp. strain Chol1 releasing intermediates with a 3-keto-Δ1,4-diene structure of the steroid skeleton. The actinobacterium Dietzia sp. strain Chol2 degraded Cholate via a different and yet unexplored reaction sequence releasing intermediates with a 3-keto-Δ4,6-diene-7-deoxy structure of the steroid skeleton such as 3,12-dioxo-4,6-choldienoic acid (DOCDA). Using DOCDA as substrate, two Alphaproteobacteria, strains Chol10–11, were isolated that produced the same Cholate degradation intermediates as strain Chol2. With DOCDA as substrate for Pseudomonas sp. strain Chol1 only the side chain was degraded while the ring system was transformed into novel steroid compounds accumulating as dead-end metabolites. These metabolites could be degraded by the DOCDA-producing strains Chol10–11. These results indicate that bacteria with potentially different pathways for Cholate degradation coexist in natural habitats and may interact via interspecies cross-feeding.
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identification of a thiolase gene essential for β oxidation of the acyl side chain of the steroid compound Cholate in pseudomonas sp strain chol1
Fems Microbiology Letters, 2011Co-Authors: Antoinette Birkenmaier, Heiko M Moller, Bodo PhilippAbstract:Bile salts such as Cholate are steroid compounds occurring ubiquitously in the environment through excretion by animals. Cholate degradation by Pseudomonas sp. strain Chol1 is initiated by A-ring oxidation and β-oxidation of the acyl side chain. A transposon mutant of strain Chol1 was isolated that could not grow with Cholate, but transformed it into several steroid compounds accumulating in culture supernatants. The main product was identified as (22E)-7α,12α-dihydroxy-3-oxochola-1,4,22-triene-24-oate (DHOCTO). A further compound was identified as 7α,12α,22-trihydroxy-3-oxochola-1,4-diene-24-oate (THOCDO). The structures of DHOCTO and THOCDO indicate that they are intermediates of the β-oxidation of the acyl side chain. The interrupted gene was named skt and had similarities to the 3-ketoacyl-CoA thiolase domain of the eukaryotic sterol carrier protein SCP-x. An skt mutant grew with intermediates of Cholate degradation, from which the acyl side chain had been partly or completely removed. Growth with Cholate was restored by an intact skt copy on a plasmid. These results strongly suggest that skt encodes a β-ketothiolase responsible for the cleavage of acetyl-CoA from the acyl side chain of Cholate. Sequence comparisons revealed that other steroid-degrading bacteria such as Comamonas testosteroni contain genes encoding proteins very similar to Skt, suggesting a widespread role of this enzyme in bacterial steroid degradation.
Medini Kanta Pal - One of the best experts on this subject based on the ideXlab platform.
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Spectroscopic probes of the interactions of the dye Stains-all with deoxyCholate and Cholate
Colloids and Surfaces B: Biointerfaces, 1998Co-Authors: Adrijit Goswami, Medini Kanta PalAbstract:The biological surfactants sodium Cholate (NaC) and sodium deoxyCholate (NaDC) differ from the normal surfactants such as sodium dodecyl sulphate (SDS) by having hydrophilic -OH groups in their hydrophobic moieties, and they failed to induce sharp blue shifted metachromasia in the common cationic dyes such as acridine Orange, methylene blue, pinacyanol etc. However, both the Cholates induce extremely sharp and stable blue-shifted metachromasia in the cyanine dye Stains-all (Stal), at concentrate much below the critical micellar concentrations and not disrupted by the excess of surfactants unless at above the respective critical micellar concentrations. Both chiral Cholates induce very strong biphasic negative circular dichroism (CD) in Stal. At high surfactant dye both NaDC-Stal and NaC-Stal exhibit a second positive biphasic CD spectrum, indicating the formation of second species of the complexes, not immediately discernible from the respective absorption spectrum. Though the reported structures of micelles and crystals of NaDC are distinctly different from that of NaC, the induced metachromasia and circular dichroism in Stal by the two surfactants are remarkably similar. It is reasonably thought that Stal cations bound at NaC and NaDC are arranged with systematic twists in one sense, responsible for metachromasia and dichroism of the dye aggregates, the formation of NaDC-Stal and NaC-Stal are probably followed by some self organization of the complexes formed in the premicellar range of concentrations, excess surfactants added to these complexes form just part of the solvent. Only above cmc the micelles start disruption of the dye aggregates. Our results fit well with the helical model of NaDC and the Small's model of NaDC micellar aggregate with the hydrophobic surfaces oriented inside.
Onur Yucel - One of the best experts on this subject based on the ideXlab platform.
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an unexplored pathway for degradation of Cholate requires a 7α hydroxysteroid dehydratase and contributes to a broad metabolic repertoire for the utilization of bile salts in novosphingobium sp strain chol11
Environmental Microbiology, 2016Co-Authors: Onur Yucel, Steffen L Drees, Nina Jagmann, Thomas Patschkowski, Bodo PhilippAbstract:Bile salts such as Cholate are surface-active steroid compounds with functions for digestion and signaling in vertebrates. Upon excretion into soil and water bile salts are an electron- and carbon-rich growth substrate for environmental bacteria. Degradation of bile salts proceeds via intermediates with a 3-keto-Δ1,4-diene structure of the steroid skeleton as shown for e.g. Pseudomonas spp. Recently, we isolated bacteria degrading Cholate via intermediates with a 3-keto-7-deoxy-Δ4,6-structure of the steroid skeleton suggesting the existence of a second pathway for Cholate degradation. This potential new pathway was investigated with Novosphingobium sp. strain Chol11. A 7α-hydroxysteroid dehydratase encoded by hsh2 was identified, which was required for the formation of 3-keto-7-deoxy-Δ4,6-metabolites. A hsh2 deletion mutant could still grow with Cholate but showed impaired growth. Cholate degradation of this mutant proceeded via 3-keto-Δ1,4-diene metabolites. Heterologous expression of Hsh2 in the bile salt-degrading Pseudomonas sp. strain Chol1 led to formation of a dead-end steroid with a 3-keto-7-deoxy-Δ4,6-diene structure. Hsh2 is the first steroid dehydratase with an important function in a metabolic pathway of bacteria that use bile salts as growth substrates. This pathway contributes to a broad metabolic repertoire of Novosphingobium strain Chol11 that may be advantageous in competition with other bile salt-degrading bacteria. This article is protected by copyright. All rights reserved.
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evidence of distinct pathways for bacterial degradation of the steroid compound Cholate suggests the potential for metabolic interactions by interspecies cross feeding
Environmental Microbiology, 2014Co-Authors: Johannes Holert, Onur Yucel, Vemparthan Suvekbala, žarko Kulic, Heiko M Moller, Bodo PhilippAbstract:Summary The distribution and the metabolic pathways of bacteria degrading steroid compounds released by eukaryotic organisms were investigated using the bile salt Cholate as model substrate. Cholate-degrading bacteria could be readily isolated from freshwater environments. All isolated strains transiently released steroid degradation intermediates into culture supernatants before their further degradation. Cholate degradation could be initiated via two different reaction sequences. Most strains degraded Cholate via a reaction sequence known from the model organism Pseudomonas sp. strain Chol1 releasing intermediates with a 3-keto-Δ1,4-diene structure of the steroid skeleton. The actinobacterium Dietzia sp. strain Chol2 degraded Cholate via a different and yet unexplored reaction sequence releasing intermediates with a 3-keto-Δ4,6-diene-7-deoxy structure of the steroid skeleton such as 3,12-dioxo-4,6-choldienoic acid (DOCDA). Using DOCDA as substrate, two Alphaproteobacteria, strains Chol10–11, were isolated that produced the same Cholate degradation intermediates as strain Chol2. With DOCDA as substrate for Pseudomonas sp. strain Chol1 only the side chain was degraded while the ring system was transformed into novel steroid compounds accumulating as dead-end metabolites. These metabolites could be degraded by the DOCDA-producing strains Chol10–11. These results indicate that bacteria with potentially different pathways for Cholate degradation coexist in natural habitats and may interact via interspecies cross-feeding.