Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.2.1.13 (acetyl-CoA synthetase)
 451 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The physiology of Hanseniaspora uvarum K5 was studied in glucose-limited chemostat cultures and upon glucose pulse. Up to a dilution rate of 0.28 h-1, glucose was completely metabolized in biomass and CO2. Above this value, increase in the dilution rate was accompanied by sequential production of metabolites (glycerol, acetate and ethanol) and decrease in cell yield. Similar results were observed upon glucose pulse. From the enzyme activities (pyruvate dehydrogenase, pyruvate decarboxylase, NAD and NADP-dependent acetaldehyde dehydrogenases, acetyl coenzyme A synthetase and alcohol dehydrogenase) and substrate affinities, the following conclusions were drawn with respect to product formation of cells: (1) pyruvate was preferentially metabolized via pyruvate dehydrogenase, when biomass and CO2 were the only products formed; (2) acetaldehyde formed by pyruvate decarboxylase was preferentially oxidized in acetate by NADP-dependent aldehyde dehydrogenase; acetate accumulation results from insufficient activity of acetyl-CoA synthetase required for the complete oxidation of acetate; (3) acetaldehyde was oxidized in ethanol by alcohol dehydrogenase, in addition to acetate production.
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PMID:Glucose metabolism, enzymic analysis and product formation in chemostat culture of Hanseniaspora uvarum. 778 33

O-acetylhomoserine (OAH) is a promising platform chemical for the production of l-methionine and other valuable compounds. However, the relative low titer and yield of OAH greatly limit its industrial production and cost-effective application. In this study, we successfully constructed an efficient OAH-producing strain with high titer and yield by combining protein and metabolic engineering strategies in E. coli. Initially, an OAH-producing strain was created by reconstruction of biosynthetic pathway and deletion of degradation and competitive pathways, which accumulated 1.68 g/L of OAH. Subsequently, several metabolic engineering strategies were implemented to improve the production of OAH. The pathway flux of OAH was enhanced by eliminating byproduct accumulation, increasing oxaloacetate supply and promoting the biosynthesis of precursor homoserine, resulting in a 1.79-fold increase in OAH production. Moreover, protein engineering was applied to improve the properties of the rate-limiting enzyme homoserine acetyltransferase (MetXlm) based on evolutionary conservation analysis and structure-guided engineering. The resulting triple F147L-M182I-M240A mutant of MetXlm exhibited a 12.15-fold increase in specific activity, and the optimized expression of the MetXlm mutant led to a 57.14% improvement in OAH production. Furthermore, the precursor acetyl-CoA supply and NADPH generation were also enhanced to facilitate the biosynthesis of OAH by promoting CoA biosynthesis, overexpressing heterogeneous acetyl-CoA synthetase (ACS), and introducing NADP-dependent pyruvate dehydrogenase (PDH). Finally, the engineered strain OAH-7 produced 62.7 g/L of OAH with yield and productivity values of 0.45 g/g glucose and 1.08 g/L/h, respectively, in a 7.5 L fed-batch fermenter, which was the highest OAH production ever reported.
ACS Synth Biol 2019 05 17
PMID:Combining Protein and Metabolic Engineering Strategies for High-Level Production of O-Acetylhomoserine in Escherichia coli. 3097 96


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