Thorough research and modification of one-carbon units cycle for improving L-methionine production in .

Unlabelled: Methionine is the only one of the essential amino acids that contain sulfur, widely used as a feed additive in agriculture. In this study, the availability of 5-methyl-tetrahydrofolate was confirmed as the main limitation in the complex multibranched biosynthetic pathway of L-methionine. The cycle of one-carbon units was thoroughly investigated and modified to supply 5-methyl-tetrahydrofolate for L-methionine production, such as enhancing the supply of precursor, expediting the conversion rate of the cycle, introducing exogenous serine hydroxymethyltransferase and increasing pool size of one-carbon units carrier.

Construction of exogenous methanol, formate, and betaine modules for methyl donor supply in methionine biosynthesis.

Methionine is an essential sulfur-containing amino acid that finds widespread applications in agriculture, medicine, and the food industry. However, the complex and multibranched biosynthetic pathway of methionine has posed significant challenges to its efficient fermentation production. In this study, we employed a modularized synthetic biology strategy to improve the weakest branched pathway of methionine biosynthesis.

Local metabolic response of Escherichia coli to the module genetic perturbations in l-methionine biosynthetic pathway.

l-Methionine biosynthesis is through multilevel regulated and multibranched biosynthetic pathway (MRMBP). Because of the complex regulatory mechanism and the imbalanced metabolic flux between branched pathways, microbial production of l-methionine has not been commercialized. In this study, local metabolic response in MRMBP of l-methionine was investigated and various crucial genes in branched pathways were determined.

Enhanced amphotericin B production by genetically engineered Streptomyces nodosus.

The antifungal agent amphotericin B (AmB) is a polyketide produced by Streptomyces nodosus. The synthetic precursors of the amphotericin macrolactone skeleton are acetyl-CoA, malonyl-CoA and methylmalonyl-CoA. The genome sequence of the wild type S.

The efficacy and safety of balloon dilation for unresectable malignant biliary obstruction before placement of self-expanding metal stents.

Objective: To evaluate whether patients with malignant biliary obstruction (MBO) benefit from balloon dilation before the placement of a self-expanding metal stent (SEMS) for palliative biliary drainage.

Methods: Consecutive patients who underwent endoscopic retrograde cholangiopancreatography with SEMS placement for palliative management of MBO were retrospectively included. Comparative analyses of serum bilirubin levels, post-procedural adverse events, stent patency time, stent dysfunction, and patient survival were performed between the dilation and non-dilation groups.

Systematic Analysis of Bottlenecks in a Multibranched and Multilevel Regulated Pathway: The Molecular Fundamentals of l-Methionine Biosynthesis in Escherichia coli.

To produce chemicals and fuels from renewable resources, various strategies and genetic tools have been developed to redesign pathways and optimize the metabolic flux in microorganisms. However, in most successful cases, the target chemicals are synthesized through a linear pathway, and regular methodologies for the identification of bottlenecks and metabolic flux optimization in multibranched and multilevel regulated pathways, such as the l-methionine biosynthetic pathway, have rarely been reported. In the present study, a systematic analysis strategy was employed to gradually reveal and remove the potential bottlenecks limiting the l-methionine biosynthesis in E.

Metabolic engineering of for the production of -succinyl-l-homoserine with high yield.

-succinyl-l-homoserine (OSH) is a promising platform chemical for the production of C4 chemicals with huge market potential which can be produced by fermentation from glucose. To construct a strain capable of producing OSH with high yield, the (encodes transcriptional repressor) and (encodes a subunit of dl-methionine transporter) were deleted in W3110 to obtain a strain ∆JI. Then, overexpression of (encodes bifunctional aspartate kinase/homoserine dehydrogenase II) and inactivation of (encodes cystathionine γ-synthase) were implemented in one step, and the OSH titer of the resulting strain ∆JIB Trc was dramatically increased to 7.

Metabolic engineering of Escherichia coli for microbial production of L-methionine.

L-methionine has attracted a great deal of attention for its nutritional, pharmaceutical, and clinical applications. In this study, Escherichia coli W3110 was engineered via deletion of a negative transcriptional regulator MetJ and over-expression of homoserine O-succinyltransferase MetA together with efflux transporter YjeH, resulting in L-methionine overproduction which is up to 413.16 mg/L.

Upscale production of ethyl (S)-4-chloro-3-hydroxybutanoate by using carbonyl reductase coupled with glucose dehydrogenase in aqueous-organic solvent system.

(S)-4-chloro-3-hydroxybutanoate ((S)-CHBE) is an important chiral intermediate to synthesize the side chain of cholesterol-lowering drug atorvastatin. To biosynthesize the (S)-CHBE, a recombinant Escherichia coli harboring the carbonyl reductase and glucose dehydrogenase was successfully constructed. The recombinant E.