- Identification of an α-Oxoamine Synthase and a One-Pot Two-Step Enzymatic Synthesis of α-Amino Ketones
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Alb29, an α-oxoamine synthase involved in albogrisin biosynthesis in Streptomyces albogriseolus MGR072, was characterized and responsible for the incorporation of l-glutamate to acyl-coenzyme A substrates. Combined with Alb29 and Mgr36 (an acyl-coenzyme A ligase), a one-pot enzymatic system was established to synthesize seven α-amino ketones. When these α-amino ketones were fed into the alb29 knockout strain Δalb29, respectively, the albogrisin analogs with different side chains were observed.
- Zhou, Ting,Gao, Du,Li, Jia-Xin,Xu, Min-Juan,Xu, Jun
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supporting information
p. 37 - 41
(2020/12/21)
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- Repurposing the 3-Isocyanobutanoic Acid Adenylation Enzyme SfaB for Versatile Amidation and Thioesterification
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Genome mining of microbial natural products enables chemists not only to discover the bioactive molecules with novel skeletons, but also to identify the enzymes that catalyze diverse chemical reactions. Exploring the substrate promiscuity and catalytic mechanism of those biosynthetic enzymes facilitates the development of potential biocatalysts. SfaB is an acyl adenylate-forming enzyme that adenylates a unique building block, 3-isocyanobutanoic acid, in the biosynthetic pathway of the diisonitrile natural product SF2768 produced by Streptomyces thioluteus, and this AMP-ligase was demonstrated to accept a broad range of short-chain fatty acids (SCFAs). Herein, we repurpose SfaB to catalyze amidation or thioesterification between those SCFAs and various amine or thiol nucleophiles, thereby providing an alternative enzymatic approach to prepare the corresponding amides and thioesters in vitro.
- Zhu, Mengyi,Wang, Lijuan,He, Jing
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supporting information
p. 2030 - 2035
(2020/11/30)
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- ATP Regeneration System in Chemoenzymatic Amide Bond Formation with Thermophilic CoA Ligase
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CoA ligases are enzymes catalyzing the ATP-dependent addition of coenzyme A to carboxylic acids in two steps through an adenylate intermediate. This intermediate can be diverted by a nucleophilic non enzymatic addition of amine to get the corresponding amide for synthetic purposes. To this end, we selected thermophilic CoA ligases to study the conversion of various carboxylic acids into their amide counterparts. To limit the use of ATP, we implemented an ATP regeneration system combining polyphosphate kinase 2 (PPK2 Class III) and inorganic pyrophosphatase. Suitability of this system was illustrated by the lab-scale chemoenzymatic synthesis of N-methylbutyrylamide in 77 % yield using low enzyme loading and 5 % molar ATP.
- Lelièvre, Chloé M.,Balandras, Mélanie,Petit, Jean-Louis,Vergne-Vaxelaire, Carine,Zaparucha, Anne
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p. 1184 - 1189
(2020/01/22)
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- Structural Mechanism of Regioselectivity in an Unusual Bacterial Acyl-CoA Dehydrogenase
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Terminal alkenes are easily derivatized, making them desirable functional group targets for polyketide synthase (PKS) engineering. However, they are rarely encountered in natural PKS systems. One mechanism for terminal alkene formation in PKSs is through the activity of an acyl-CoA dehydrogenase (ACAD). Herein, we use biochemical and structural analysis to understand the mechanism of terminal alkene formation catalyzed by an ?,?-ACAD from the biosynthesis of the polyketide natural product FK506, TcsD. While TcsD is homologous to canonical α,β-ACADs, it acts regioselectively at the ?,?-position and only on α,β-unsaturated substrates. Furthermore, this regioselectivity is controlled by a combination of bulky residues in the active site and a lateral shift in the positioning of the FAD cofactor within the enzyme. Substrate modeling suggests that TcsD utilizes a novel set of hydrogen bond donors for substrate activation and positioning, preventing dehydrogenation at the α,β position of substrates. From the structural and biochemical characterization of TcsD, key residues that contribute to regioselectivity and are unique to the protein family were determined and used to identify other putative ?,?-ACADs that belong to diverse natural product biosynthetic gene clusters. These predictions are supported by the demonstration that a phylogenetically distant homologue of TcsD also regioselectively oxidizes α,β-unsaturated substrates. This work exemplifies a powerful approach to understand unique enzymatic reactions and will facilitate future enzyme discovery, inform enzyme engineering, and aid natural product characterization efforts.
- Adams, Paul D.,Alonso-Martinez, Catalina,Baidoo, Edward E. K.,Barajas, Jesus F.,Blake-Hedges, Jacquelyn M.,Chan, Leanne Jade G.,Chen, Jeffrey,Chen, Yan,Cruz-Morales, Pablo,Gin, Jennifer W.,Katz, Leonard,Keasling, Jay D.,Krishna, Rohith N.,Nimlos, Danika,Pereira, Jose Henrique,Petzold, Christopher J.,Thompson, Mitchell G.
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supporting information
p. 835 - 846
(2020/02/20)
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- A HOST CELL MODIFIED TO PRODUCE LACTAMS
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The present invention provides for a genetically modified host cell capable of producing a lactam comprising a 2-pyrrolidone synthase, or an enzymatically active fragment thereof, heterologous to the host cell.
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Paragraph 0097-0098; 00109
(2018/01/15)
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- Screening and Engineering the Synthetic Potential of Carboxylating Reductases from Central Metabolism and Polyketide Biosynthesis
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Carboxylating enoyl-thioester reductases (ECRs) are a recently discovered class of enzymes. They catalyze the highly efficient addition of CO2 to the double bond of α,β-unsaturated CoA-thioesters and serve two biological functions. In primary metabolism of many bacteria they produce ethylmalonyl-CoA during assimilation of the central metabolite acetyl-CoA. In secondary metabolism they provide distinct α-carboxyl-acyl-thioesters to vary the backbone of numerous polyketide natural products. Different ECRs were systematically assessed with a diverse library of potential substrates. We identified three active site residues that distinguish ECRs restricted to C4 and C5-enoyl-CoAs from highly promiscuous ECRs and successfully engineered a selected ECR as proof-of-principle. This study defines the molecular basis of ECR reactivity, allowing for predicting and manipulating a key reaction in natural product diversification.
- Peter, Dominik M.,Schada Von Borzyskowski, Lennart,Kiefer, Patrick,Christen, Philipp,Vorholt, Julia A.,Erb, Tobias J.
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p. 13457 - 13461
(2015/11/09)
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- Substrate specificity, substrate channeling, and allostery in BphJ: An acylating aldehyde dehydrogenase associated with the pyruvate aldolase BphI
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BphJ, a nonphosphorylating acylating aldehyde dehydrogenase, catalyzes the conversion of aldehydes to form acyl-coenzyme A in the presence of NAD + and coenzyme A (CoA). The enzyme is structurally related to the nonacylating aldehyde dehydrogenases, aspartate-β-semialdehyde dehydrogenase and phosphorylating glyceraldehyde-3-phosphate dehydrogenase. Cys-131 was identified as the catalytic thiol in BphJ, and pH profiles together with site-specific mutagenesis data demonstrated that the catalytic thiol is not activated by an aspartate residue, as previously proposed. In contrast to the wild-type enzyme that had similar specificities for two- or three-carbon aldehydes, an I195A variant was observed to have a 20-fold higher catalytic efficiency for butyraldehyde and pentaldehyde compared to the catalytic efficiency of the wild type toward its natural substrate, acetaldehyde. BphJ forms a heterotetrameric complex with the class II aldolase BphI that channels aldehydes produced in the aldol cleavage reaction to the dehydrogenase via a molecular tunnel. Replacement of Ile-171 and Ile-195 with bulkier amino acid residues resulted in no more than a 35% reduction in acetaldehyde channeling efficiency, showing that these residues are not critical in gating the exit of the channel. Likewise, the replacement of Asn-170 in BphJ with alanine and aspartate did not substantially alter aldehyde channeling efficiencies. Levels of activation of BphI by BphJ N170A, N170D, and I171A were reduced by ≥3-fold in the presence of NADH and ≥4.5-fold when BphJ was undergoing turnover, indicating that allosteric activation of the aldolase has been compromised in these variants. The results demonstrate that the dehydrogenase coordinates the catalytic activity of BphI through allostery rather than through aldehyde channeling. (Figure Presented).
- Baker, Perrin,Carere, Jason,Seah, Stephen Y. K.
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experimental part
p. 4558 - 4567
(2012/09/10)
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- Establishing a toolkit for precursor-directed polyketide biosynthesis: Exploring substrate promiscuities of acid-CoA ligases
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Polyketides are chemically diverse and medicinally important biochemicals that are biosynthesized from acyl-CoA precursors by polyketide synthases. One of the limitations to combinatorial biosynthesis of polyketides has been the lack of a toolkit that describes the means of delivering novel acyl-CoA precursors necessary for polyketide biosynthesis. Using five acid-CoA ligases obtained from various plants and microorganisms, we biosynthesized an initial library of 79 acyl-CoA thioesters by screening each of the acid-CoA ligases against a library of 123 carboxylic acids. The library of acyl-CoA thioesters includes derivatives of cinnamyl-CoA, 3-phenylpropanoyl-CoA, benzoyl-CoA, phenylacetyl-CoA, malonyl-CoA, saturated and unsaturated aliphatic CoA thioesters, and bicyclic aromatic CoA thioesters. In our search for the biosynthetic routes of novel acyl-CoA precursors, we discovered two previously unreported malonyl-CoA derivatives (3-thiophenemalonyl-CoA and phenylmalonyl-CoA) that cannot be produced by canonical malonyl-CoA synthetases. This report highlights the utility and importance of determining substrate promiscuities beyond conventional substrate pools and describes novel enzymatic routes for the establishment of precursor-directed combinatorial polyketide biosynthesis. (Chemical Presented).
- Go, Maybelle Kho,Chow, Jeng Yeong,Cheung, Vivian Wing Ngar,Lim, Yan Ping,Yew, Wen Shan
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experimental part
p. 4568 - 4579
(2012/08/28)
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- Hepatic enzymatic synthesis and hydrolysis of CoA esters of solvent-derived oxa acids
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Many ethylene glycol-derived solvents are oxidized to xenobiotic alkoxyacetic acids (3-oxa acids) by hepatic enzymes. The toxicity of these ubiquitous solvents has been associated with their oxa acid metabolites. For many xenobiotic carboxylic acids, the toxicity is associated with the CoA ester of the acid. In this study, related alkoxyacetic acids were evaluated as potential substrates for acyl-CoA synthetases found in mitochondrial, peroxisomal, and microsomal fractions isolated from rat liver. Likewise, chemically synthesized oxa acyl-CoAs were used as substrates for acyl-CoA hydrolases associated with the same rat liver fractions. Activities of the xenobiotic oxygen-substituted substrates were compared with analogous physiologic aliphatic substrates by UV-vis spectrophotometric methods. All of the solvent-derived oxa acids were reasonable substrates for the acyl-CoA synthetases, although their activity was usually less than the corresponding physiologic acid. Acyl-CoA hydrolase activities were decreased compared with acyl-CoA synthetase activities for all substrates, especially for the oxa acyl-CoAs. These studies suggest that these xenobiotic carboxylic acids may be converted to reactive acyl-CoA moieties which will persist in areas of the cell proximal to lipid synthesis, β-oxidation, protein acylation, and amino acid conjugation. The interaction of these xenobiotic acyl-CoAs with those processes may be important to their toxicity and/or detoxification.
- Panuganti, Sree D.,Penn, Jill M.,Moore, Kathleen H.
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