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Bahrami Moghadam E, Nguyen N, Wang Y, Cirino PC. Directed Evolution of Protein-Based Sensors for Anaerobic Biological Activation of Methane. BIOSENSORS 2024; 14:325. [PMID: 39056601 PMCID: PMC11275114 DOI: 10.3390/bios14070325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Revised: 06/24/2024] [Accepted: 06/27/2024] [Indexed: 07/28/2024]
Abstract
Microbial alkane degradation pathways provide biological routes for converting these hydrocarbons into higher-value products. We recently reported the functional expression of a methyl-alkylsuccinate synthase (Mas) system in Escherichia coli, allowing for the heterologous anaerobic activation of short-chain alkanes. However, the enzymatic activation of methane via natural or engineered alkylsuccinate synthases has yet to be reported. To address this, we employed high-throughput screening to engineer the itaconate (IA)-responsive regulatory protein ItcR (WT-ItcR) from Yersinia pseudotuberculosis to instead respond to methylsuccinate (MS, the product of methane addition to fumarate), resulting in genetically encoded biosensors for MS. Here, we describe ItcR variants that, when regulating fluorescent protein expression in E. coli, show increased sensitivity, improved overall response, and enhanced specificity toward exogenously added MS relative to the wild-type repressor. Structural modeling and analysis of the ItcR ligand binding pocket provide insights into the altered molecular recognition. In addition to serving as biosensors for screening alkylsuccinate synthases capable of methane activation, MS-responsive ItcR variants also establish a framework for the directed evolution of other molecular reporters, targeting longer-chain alkylsuccinate products or other succinate derivatives.
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Affiliation(s)
| | | | | | - Patrick C. Cirino
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204-4004, USA; (E.B.M.)
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Bruns S, Cakić N, Mitschke N, Kopke BJ, Rabus R, Wilkes H. A Novel Coenzyme A Analogue in the Anaerobic, Sulfate-Reducing, Marine Bacterium Desulfobacula toluolica Tol2 T. Chembiochem 2023; 24:e202200584. [PMID: 36331165 PMCID: PMC10107677 DOI: 10.1002/cbic.202200584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/03/2022] [Accepted: 11/03/2022] [Indexed: 11/06/2022]
Abstract
Coenzyme A (CoA) thioesters are formed during anabolic and catabolic reactions in every organism. Degradation pathways of growth-supporting substrates in bacteria can be predicted by differential proteogenomic studies. Direct detection of proposed metabolites such as CoA thioesters by high-performance liquid chromatography coupled with high-resolution mass spectrometry can confirm the reaction sequence and demonstrate the activity of these degradation pathways. In the metabolomes of the anaerobic sulfate-reducing bacterium Desulfobacula toluolica Tol2T grown with different substrates various CoA thioesters, derived from amino acid, fatty acid or alcohol metabolism, have been detected. Additionally, the cell extracts of this bacterium revealed a number of CoA analogues with molecular masses increased by 1 dalton. By comparing the chromatographic and mass spectrometric properties of synthetic reference standards with those of compounds detected in cell extracts of D. toluolica Tol2T and by performing co-injection experiments, these analogues were identified as inosino-CoAs. These CoA thioesters contain inosine instead of adenosine as the nucleoside. To the best of our knowledge, this finding represents the first detection of naturally occurring inosino-CoA analogues.
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Affiliation(s)
- Stefan Bruns
- Institute for Chemistry and Biology of the, Marine Environment (ICBM), Organic Geochemistry, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Nevenka Cakić
- Institute for Chemistry and Biology of the, Marine Environment (ICBM), Organic Geochemistry, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Nico Mitschke
- Institute for Chemistry and Biology of the, Marine Environment (ICBM), Marine Geochemistry, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Bernd Johann Kopke
- Institute for Chemistry and Biology of the, Marine Environment (ICBM), Organic Geochemistry, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Ralf Rabus
- Institute for Chemistry and Biology of the, Marine Environment (ICBM), General and Molecular Microbiology, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Heinz Wilkes
- Institute for Chemistry and Biology of the, Marine Environment (ICBM), Organic Geochemistry, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
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Wang Y, Nguyen N, Lee SH, Wang Q, May JA, Gonzalez R, Cirino PC. Engineering Escherichia coli for anaerobic alkane activation: Biosynthesis of (1-methylalkyl)succinates. Biotechnol Bioeng 2021; 119:315-320. [PMID: 34633065 DOI: 10.1002/bit.27956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 09/28/2021] [Accepted: 10/03/2021] [Indexed: 11/11/2022]
Abstract
In anoxic environments, microbial activation of alkanes for subsequent metabolism occurs most commonly through the addition of fumarate to a subterminal carbon, producing an alkylsuccinate. Alkylsuccinate synthases are complex, multi-subunit enzymes that utilize a catalytic glycyl radical and require a partner, activating enzyme for hydrogen abstraction. While many genes encoding putative alkylsuccinate synthases have been identified, primarily from nitrate- and sulfate-reducing bacteria, few have been characterized and none have been reported to be functionally expressed in a heterologous host. Here, we describe the functional expression of the (1-methylalkyl)succinate synthase (Mas) system from Azoarcus sp. strain HxN1 in recombinant Escherichia coli. Mass spectrometry confirms anaerobic biosynthesis of the expected products of fumarate addition to hexane, butane, and propane. Maximum production of (1-methylpentyl)succinate is observed when masC, masD, masE, masB, and masG are all present on the expression plasmid; omitting masC reduces production by 66% while omitting any other gene eliminates production. Meanwhile, deleting iscR (encoding the repressor of the E. coli iron-sulfur cluster operon) improves product titer, as does performing the biotransformation at reduced temperature (18°C), both suggesting alkylsuccinate biosynthesis is largely limited by functional expression of this enzyme system.
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Affiliation(s)
- Yixi Wang
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
| | - Nam Nguyen
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
| | - Seung H Lee
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida, USA.,Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
| | - Qinxuan Wang
- Department of Chemistry, University of Houston, Houston, Texas, USA
| | - Jeremy A May
- Department of Chemistry, University of Houston, Houston, Texas, USA
| | - Ramon Gonzalez
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida, USA
| | - Patrick C Cirino
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
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Mitschke N, Eruçar G, Fsadni MH, Roberts AR, Sadeghi MM, Golding BT, Christoffers J, Wilkes H. Enantiopure 2,9‐Dideuterodecane – Preparation and Proof of Enantiopurity. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Nico Mitschke
- Institut für Chemie Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
- Institut für Chemie und Biologie des Meeres (ICBM) Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
| | - Gülsera Eruçar
- Institut für Chemie Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
| | - Miriam H. Fsadni
- School of Natural & Environmental Sciences, Bedson Building Newcastle University NE1 7RU Newcastle upon Tyne UK
| | - Amy R. Roberts
- School of Natural & Environmental Sciences, Bedson Building Newcastle University NE1 7RU Newcastle upon Tyne UK
| | - Majid M. Sadeghi
- School of Natural & Environmental Sciences, Bedson Building Newcastle University NE1 7RU Newcastle upon Tyne UK
| | - Bernard T. Golding
- School of Natural & Environmental Sciences, Bedson Building Newcastle University NE1 7RU Newcastle upon Tyne UK
| | - Jens Christoffers
- Institut für Chemie Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
| | - Heinz Wilkes
- Institut für Chemie und Biologie des Meeres (ICBM) Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
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Mitschke N, Jarling R, Rabus R, Christoffers J, Wilkes H. Metabolites of the anaerobic degradation of diethyl ether by denitrifying betaproteobacterium strain HxN1. Org Biomol Chem 2020; 18:7098-7109. [PMID: 32897282 DOI: 10.1039/d0ob01419b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
The constitutions of five metabolites formed during co-metabolic, anaerobic degradation of diethyl ether by the denitrifying betaproteobacterium Aromatoleum sp. strain HxN1 were elucidated by comparison of mass spectrometric and gas chromatographic data with those of synthetic reference standards. Furthermore, the absolute configurations of two stereogenic centers in the metabolites were established. Based on these results a degradation pathway for diethyl ether by Aromatoleum sp. HxN1 analogous to that of n-hexane is proposed. Synthesis of both enantiomers of methyl (E)-4-ethoxy-2-pentenoate was accomplished by etherification of ethyl (R)- or (S)-lactate, followed by hydrolysis of the ester group and reduction to furnish 2-ethoxy-1-propanol. The primary alcohol was converted by a Swern oxidation followed by a Horner-Wadsworth-Emmons reaction to methyl (E)-4-ethoxy-2-pentenoate that was finally hydrogenated to methyl 4-ethoxypentanoate. Methyl (S)-4-ethoxy-3-oxopentanoate was prepared by conversion of (S)-2-ethoxypropanoyl chloride with Meldrum's acid. Reduction of the resulting β-oxoester with NaBH4 or baker's yeast gave both diastereoisomers of methyl 4-ethoxy-3-hydroxypentanoate. The stereocenter at C-3 of the main diastereoisomer produced with baker's yeast was determined by Mosher ester analysis to be (R)-configurated. Dimethyl 2-(1-ethoxyethyl)succinate was prepared by Michael addition of nitroethane to diethyl maleate, followed by conjugate addition of sodium ethanolate, hydrolysis and esterification with diazomethane.
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Affiliation(s)
- Nico Mitschke
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111 Oldenburg, Germany.
| | - René Jarling
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111 Oldenburg, Germany.
| | - Ralf Rabus
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111 Oldenburg, Germany.
| | - Jens Christoffers
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, 26111 Oldenburg, Germany.
| | - Heinz Wilkes
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111 Oldenburg, Germany.
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Küppers J, Mitschke N, Heyen S, Rabus R, Wilkes H, Christoffers J. Metabolites of the Anaerobic Degradation of n-Hexane by Denitrifying Betaproteobacterium Strain HxN1. Chembiochem 2020; 21:373-380. [PMID: 31294892 PMCID: PMC7028053 DOI: 10.1002/cbic.201900375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Indexed: 11/05/2022]
Abstract
The constitutions of seven metabolites formed during anaerobic degradation of n-hexane by the denitrifying betaproteobacterium strain HxN1 were elucidated by comparison of their GC and MS data with those of synthetic reference standards. The synthesis of 4-methyloctanoic acid derivatives was accomplished by the conversion of 2-methylhexanoyl chloride with Meldrum's acid. The β-oxoester was reduced with NaBH4 , the hydroxy group was eliminated, and the double bond was displaced to yield the methyl esters of 4-methyl-3-oxooctanoate, 3-hydroxy-4-methyloctanoate, (E)-4-methyl-2-octenoate, and (E)- and (Z)-4-methyl-3-octenoate. The methyl esters of 2-methyl-3-oxohexanoate and 3-hydroxy-2-methylhexanoate were similarly prepared from butanoyl chloride and Meldrum's acid. However, methyl (E)-2-methyl-2-hexenoate was prepared by Horner-Wadsworth-Emmons reaction, followed by isomerization to methyl (E)-2-methyl-3-hexenoate. This investigation, with the exception of 4-methyl-3-oxooctanoate, which was not detectable in the cultures, completes the unambiguous identification of all intermediates of the anaerobic biodegradation of n-hexane to 2-methyl-3-oxohexanoyl coenzyme A (CoA), which is then thiolytically cleaved to butanoyl-CoA and propionyl-CoA; these two metabolites are further transformed according to established pathways.
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Affiliation(s)
- Julian Küppers
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Nico Mitschke
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Simone Heyen
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Ralf Rabus
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Heinz Wilkes
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Jens Christoffers
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
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