10018-93-6Relevant articles and documents
Human Δ3,Δ2-enoyl-CoA isomerase, type 2: A structural enzymology study on the catalytic role of its ACBP domain and helix-10
Onwukwe, Goodluck U.,Kursula, Petri,Koski, M. Kristian,Schmitz, Werner,Wierenga, Rik K.
, p. 746 - 768 (2015)
The catalytic domain of the trimeric human Δ3,Δ2-enoyl-CoA isomerase, type 2 (HsECI2), has the typical crotonase fold. In the active site of this fold two main chain NH groups form an oxyanion hole for binding the thioester oxygen of the 3E- or 3Z-enoyl-CoA substrate molecules. A catalytic glutamate is essential for the proton transfer between the substrate C2 and C4 atoms for forming the product 2E-enoyl-CoA, which is a key intermediate in the β-oxidation pathway. The active site is covered by the C-terminal helix-10. In HsECI2, the isomerase domain is extended at its N terminus by an acyl-CoA binding protein (ACBP) domain. Small angle X-ray scattering analysis of HsECI2 shows that the ACBP domain protrudes out of the central isomerase trimer. X-ray crystallography of the isomerase domain trimer identifies the active site geometry. A tunnel, shaped by loop-2 and extending from the catalytic site to bulk solvent, suggests a likely mode of binding of the fatty acyl chains. Calorimetry data show that the separately expressed ACBP and isomerase domains bind tightly to fatty acyl-CoA molecules. The truncated isomerase variant (without ACBP domain) has significant enoyl-CoA isomerase activity; however, the full-length isomerase is more efficient. Structural enzymological studies of helix-10 variants show the importance of this helix for efficient catalysis.
Extending carbon chain length of 1-butanol pathway for 1-hexanol synthesis from glucose by engineered Escherichia coli
Dekishima, Yasumasa,Lan, Ethan I.,Shen, Claire R.,Cho, Kwang Myung,Liao, James C.
, p. 11399 - 11401 (2011)
An Escherichia coli strain was engineered to synthesize 1-hexanol from glucose by extending the coenzyme A (CoA)-dependent 1-butanol synthesis reaction sequence catalyzed by exogenous enzymes. The C4-acyl-CoA intermediates were first synthesized via acetyl-CoA acetyltransferase (AtoB), 3-hydroxybutyryl-CoA dehydrogenase (Hbd), crotonase (Crt), and trans-enoyl-CoA reductase (Ter) from various organisms. The butyryl-CoA synthesized was further extended to hexanoyl-CoA via β-ketothiolase (BktB), Hbd, Crt, and Ter. Finally, hexanoyl-CoA was reduced to yield 1-hexanol by aldehyde/alcohol dehydrogenase (AdhE2). Enzyme activities for the C6 intermediates were confirmed by assays using HPLC and GC. 1-Hexanol was secreted to the fermentation medium under anaerobic conditions. Furthermore, co-expressing formate dehydrogenase (Fdh) from Candida boidinii increased the 1-hexanol titer. This demonstration of 1-hexanol production by extending the 1-butanol pathway provides the possibility to produce other medium chain length alcohols using the same strategy.
Structural Mechanism of Regioselectivity in an Unusual Bacterial Acyl-CoA Dehydrogenase
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.
, p. 835 - 846 (2020)
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.
In vitro studies of maleidride-forming enzymes
Yin, Sen,Friedrich, Steffen,Hrupins, Vjaceslavs,Cox, Russell J.
, p. 14922 - 14931 (2021/05/19)
In vitro assays of enzymes involved in the biosynthesis of maleidrides from polyketides in fungi were performed. The results show that the enzymes are closely related to primary metabolism enzymes of the citric acid cycle in terms of stereochemical preferences, but with an expanded substrate selectivity. A key citrate synthase can react both saturated and unsaturated acyl CoA substrates to give solely anti substituted citrates. This undergoes anti-dehydration to afford an unsaturated precursor which is cyclised in vitro by ketosteroid-isomerase-like enzymes to give byssochlamic acid. This journal is
