[Advances in the synthesis of cytidine-5'-diphosphate choline].

Cytidine-5'-diphosphate choline (CDP-choline) plays a crucial role in the formation of the phospholipid bilamolecular layer in cell membranes and the stabilization of the neurotransmitter system, acting as a precursor to phosphatidylcholine and acetylcholine. CDP-choline has been found effective in treating functional and consciousness disorders resulting from brain injury, Parkinson's disease, depression and glaucoma, and other conditions. As such, CDP-choline is widely utilized in clinical medicine and health care products. The conventional chemical synthesis process of CDP-choline is gradually being replaced by biosynthesis due to the expensive and toxic reagents involved, the production of various by-products, and the high cost of industrial production. Biosynthesis of CDP-choline offers two strategies: microbial fermentation and biocatalysis. Microbial fermentation utilizes inexpensive raw materials but results in a relatively low conversion rate and requires a complex separation and purification process. Biocatalysis, on the other hand, involves two stages: the growth of a living "catalyst" and the conversion of the substrate. Although the synthetic process in biocatalysis is more complex, it offers a higher conversion ratio, and the downstream processing technique for extraction is relatively less costly. Consequently, biocatalysis is currently the primary strategy for the industrial production of CDP-choline. This review aims to summarize the progress made in both chemical synthesis and biosynthesis of CDP-choline, with particular focus on the metabolic pathway and the synthetic processes involved in biocatalysis, in order to provide insights for the industrial production of CDP-choline.

Coupled strategy based on regulator manipulation and medium optimization empowers the biosynthetic overproduction of lincomycin.

The biosynthesis of bioactive secondary metabolites, specifically antibiotics, is of great scientific and economic importance. The control of antibiotic production typically involves different processes and molecular mechanism. Despite numerous efforts to improve antibiotic yields, joint engineering strategies for combining genetic manipulation with fermentation optimization remain finite. Lincomycin A (Lin-A), a lincosamide antibiotic, is industrially fermented by Streptomyces lincolnensis. Herein, the leucine-responsive regulatory protein (Lrp)-type regulator SLCG_4846 was confirmed to directly inhibit the lincomycin biosynthesis, whereas indirectly controlled the transcription of SLCG_2919, the first reported repressor in S. lincolnensis. Inactivation of SLCG_4846 in the high-yield S. lincolnensis LA219X (LA219XΔ4846) increases the Lin-A production and deletion of SLCG_2919 in LA219XΔ4846 exhibits superimposed yield increment. Given the effect of the double deletion on cellular primary metabolism of S. lincolnensis, Plackett-Burman design, steepest ascent and response surface methodologies were utilized and employed to optimize the seed medium of this double mutant in shake flask, and Lin-A yield using optimal seed medium was significantly increased over the control. Above strategies were performed in a 15-L fermenter. The maximal yield of Lin-A in LA219XΔ4846-2919 reached 6.56 g/L at 216 h, 55.1 % higher than that in LA219X at the parental cultivation (4.23 g/L). This study not only showcases the potential of this strategy to boost lincomycin production, but also could empower the development of high-performance actinomycetes for other antibiotics.

QALY-type preference and willingness-to-pay among end-of-life patients with cancer treatments: a pilot study using discrete choice experiment.

PURPOSE: Quality-adjusted life-year (QALY) is a dominant measurement of health gain in economic evaluations for pricing drugs. However, end-of-life (EoL) patients' preference for QALY gains in life expectancy (LE) and quality of life (QoL) during different disease stages remains unknown and is seldom involved in decision-making. This study aims to measure preferences and willingness-to-pay (WTP) towards different types of QALY gain among EoL cancer patients. METHODS: We attributed QALY gain to four types, gain in LE and QoL, respectively, and during both progression-free survival (PFS) and post-progression survival (PPS). A discrete choice experiment including five attributes (the four QALY attributes and one cost attribute) with three levels each was developed and conducted with 85 Chinese advanced non-small cell lung cancer patients in 2022. All levels were set with QALY gain/cost synthesised from research on anti-lung cancer drugs recently listed by Chinese National Healthcare Security Administration. Each respondent answered six choice tasks in a face-to-face interview. The data were analysed using mixed logit models. RESULTS: Patients valued LE-related QALY gain in PFS most, with a relative importance of 81.8% and a WTP of $43,160 [95% CI 26,751 ~ 59,569] per QALY gain. Respondents consistently preferred LE-related to QoL-related QALY gain regardless of disease stage. Patients with higher income or lower education levels tended to pay more for QoL-related QALY gain. CONCLUSION: Our findings suggest a prioritised resource allocation to EoL-prolonging health technologies. Given the small sample size and large individual heterogeneity, a full-scale study is needed to provide more robust results.

Estimating the cost-effectiveness threshold of advanced non-small cell lung cancer in China using mean opportunity cost and contingent valuation method.

OBJECTIVES: Monetizing health has sparked controversy and has implications for pricing strategies of emerging health technologies. Medical insurance payers typically set up thresholds for quality-adjusted life years (QALY) gains based on health productivity and budget affordability, but they rarely consider patient willingness-to-pay (WTP). Our study aims to compare Chinese payer threshold and patient WTP toward QALY gain of advanced non-small cell lung cancer (NSCLC) and to inform a potential inclusion of patient WTP under more complex decision-making scenarios. METHODS: A regression model was constructed with cost as the independent variable and QALY as the dependent variable, where the regression coefficients reflect mean opportunity cost, and by transforming these coefficients, the payer threshold can be obtained. Patient WTP was elicited through a contingent valuation method survey. The robustness of the findings was examined through sensitivity analyses of model parameters and patient heterogeneity. RESULTS: The payer mean threshold in the base-case was estimated at 150,962 yuan (1.86 times per capita GDP, 95% CI 144,041-159,204). The two scenarios analysis generated by different utility inputs yielded thresholds of 112,324 yuan (1.39 times per capita GDP) and 111,824 yuan (1.38 times per capita GDP), respectively. The survey included 85 patients, with a mean WTP of 148,443 yuan (1.83 times per capita GDP, 95% CI 120,994-175,893) and median value was 106,667 yuan (1.32 times the GDP per capita). Due to the substantial degree of dispersion, the median was more representative. The payer threshold was found to have a high probability (98.5%) of falling within the range of 1-2 times per capita GDP, while the robustness of patient WTP was relatively weak. CONCLUSIONS: In China, a country with a copayment system, payer threshold was higher than patient WTP, indicating that medical insurance holds significant decision-making authority, thus temporarily negating the need to consider patient WTP.

Integrating Enzyme Evolution and Metabolic Engineering to Improve the Productivity of Γ-Aminobutyric Acid by Whole-Cell Biosynthesis in Escherichia Coli.

γ-Aminobutyric acid (GABA) is used widely in various fields, such as agriculture, food, pharmaceuticals, and biobased chemicals. Based on glutamate decarboxylase (GadBM4) derived from our previous work, three mutants, GadM4-2, GadM4-8, and GadM4-31, were obtained by integrating enzyme evolution and high-throughput screening methods. The GABA productivity obtained through whole-cell bioconversion using recombinant Escherichia coli cells harboring mutant GadBM4-2 was enhanced by 20.27% compared to that of the original GadBM4. Further introduction of the central regulator GadE of the acid resistance system and the enzymes from the deoxyxylulose-5-phosphate-independent pyridoxal 5'-phosphate biosynthesis pathway resulted in a 24.92% improvement in GABA productivity, reaching 76.70 g/L/h without any cofactor addition with a greater than 99% conversion ratio. Finally, when one-step bioconversion was applied for the whole-cell catalysis in a 5 L bioreactor, the titer of GABA reached 307.5 ± 5.94 g/L with a productivity of 61.49 g/L/h by using crude l-glutamic acid (l-Glu) as the substrate. Thus, the biocatalyst constructed above combined with the whole-cell bioconversion method represents an effective approach for industrial GABA production.

Educational attainment could be a protective factor against obstructive sleep apnea: a study based on Mendelian randomization.

BACKGROUND: Causality between education and obstructive sleep apnea (OSA) is not known. METHODS: Genetic variants, as instrumental variables for years of education, were derived from the Social Science Genetic Association Consortium. The outcome datasets related to OSA were from the FinnGen research project (www.finngen.fi/en/). Inverse variance-weighted, weighted-median, and Mendelian randomization-Egger analysis were used to estimate causal effects. To assess the robustness and horizontal pleiotropy of significant results, leave-one-out sensitivity analysis and Mendelian randomization-Egger regression analysis were conducted. The inverse variance-weighted method was undertaken to estimate the association between years of education and other known risk factors for OSA. Analyses were conducted using the Two Sample Mendelian Randomization package of R 4·0·3. RESULTS: Genetic predisposition towards 4.2 years of additional education was associated with a 27.8% lower risk of OSA [odds ratio (OR) =0.722, 95% confidence interval (CI): 0.566-0.921; P=0.009]. Sensitivity analyses were consistent with a causal interpretation in which a major bias from genetic pleiotropy was unlikely. The Mendelian randomization assumptions did not seem to be violated. Genetic predisposition towards longer education was associated with a lower body mass index, fewer cigarettes smoked per day, and greater alcohol intake per week. CONCLUSIONS: Our data indicated that education could be a protective factor against OSA. Potential mechanisms could include body mass index, tobacco smoking, and alcohol intake.

Short-term efficacy of non-pharmacological interventions for global population with elevated blood pressure: A network meta-analysis.

Background: This study aims to compare the potential short-term effects of non-pharmacological interventions (NPIs) on prehypertensive people, and provide evidence for intervention models with potential in future community-based management. Methods: In this Bayesian network meta-analysis, Pubmed, Embase, and Web of science were screened up to 16 October 2021. Prehypertensive patients (systolic blood pressure, SBP 120-139 mmHg/diastolic blood pressure, DBP 80-89 mmHg) with a follow-up period longer than 4 weeks were targeted. Sixteen NPIs were identified during the scope review and categorized into five groups. Reduction in SBP and DBP was selected as outcome variables and the effect sizes were compared using consistency models among interventions and intervention groups. Grade approach was used to assess the certainty of evidence. Results: Thirty-nine studies with 8,279 participants were included. For SBP, strengthen exercises were the most advantageous intervention group when compared with usual care (mean difference = -6.02 mmHg, 95% CI -8.16 to -3.87), and combination exercise, isometric exercise, and aerobic exercise were the three most effective specific interventions. For DBP, relaxation was the most advantageous intervention group when compared with usual care (mean difference = -4.99 mmHg, 95% CI -7.03 to -2.96), and acupuncture, meditation, and combination exercise were the three most effective specific interventions. No inconsistency was found between indirect and direct evidence. However, heterogeneity was detected in some studies. Conclusion: NPIs can bring short-term BP reduction benefits for prehypertensive patients, especially exercise and relaxation. NPIs could potentially be included in community-based disease management for prehypertensive population once long-term real-world effectiveness and cost-effectiveness are proven. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=151518, identifier: CRD42020151518.

Transcriptional regulation of a leucine-responsive regulatory protein for directly controlling lincomycin biosynthesis in Streptomyces lincolnensis.

Leucine-responsive regulatory proteins (Lrps) are a family of transcription factors involved in diverse biological processes in bacteria. So far, molecular mechanism of Lrps for regulating antibiotics biosynthesis in actinomycetes remains largely unexplored. This study, for the first time in Streptomyces lincolnensis, identified an Lrp (named as SLCG_Lrp) associated with lincomycin production. SLCG_Lrp was validated to be a positive regulator for lincomycin biosynthesis by directly stimulating transcription of two structural genes (lmbA and lmbV), three resistance genes (lmrA, lmrB and lmrC), and a regulatory gene (lmbU) within the lincomycin biosynthetic gene (lin) cluster. SLCG_Lrp was transcriptionally self-inhibited and triggered the expression of its adjacent gene SLCG_3127 encoding a LysE superfamily protein. Further, the binding site of SLCG_Lrp in the intergenic region of SLCG_3127 and SLCG_Lrp was precisely identified. Inactivation of SLCG_3127 in S. lincolnensis resulted in yield improvement of lincomycin, which was caused by intracellular accumulation of proline and cysteine. Arginine and phenylalanine were identified as specific regulatory ligands, respectively, to reduce and promote DNA-binding affinity of SLCG_Lrp. We further found that SLCG_Lrp was directly repressed by SLCG_2919, the first identified transcription factor outside lin cluster for lincomycin production. Therefore, our findings revealed SLCG_Lrp-mediated transcriptional regulation of lincomycin biosynthesis. This study extends the understanding of molecular mechanisms underlying lincomycin biosynthetic regulation.

Developmental regulator BldD directly regulates lincomycin biosynthesis in Streptomyces lincolnensis.

The regulatory mechanism of lincomycin biosynthesis remains largely unknown, although lincomycin and its derivatives have been of great application in pharmaceutical industry. As a global regulator, BldD is widespread in Streptomyces, and functions as an on-off switch to regulate the transition from morphological differentiation to secondary metabolism, inspiring us to explore scarcely regulatory realm of lincomycin biosynthesis. In this work, deletion of bldD gene (SLCG_1664) in Streptomyces lincolnensis blocked the sporulation and nearly abolished lincomycin production, while the morphological phenotype and lincomycin production were restored when introducing a functional bldD gene into the ΔbldD mutant. S. lincolnensis BldD (BldDSL) was validated to bind to upstream regions of lincomycin biosynthetic structural genes lmbA, lmbC-lmbD, lmbE, lmbV-lmbW, resistant genes lmrA, lmrB, lmrC, and regulatory gene lmbU. Disruption of bldD significantly decreased the transcription of genes in lincomycin biosynthetic cluster, thus resulting in the sharply loss of lincomycin production. These findings indicate that BldDSL, similar to Saccharopolyspora erythraea BldD (BldDSE), directly regulates the biosynthesis of lincomycin. What's more, we discovered that BldDSE could bind to upstream regions of lmbA, lmbV-lmbW, lmrA and lmrC. Corresponding to this, S. lincolnensis BldD can bind to upstream region of eryAI-eryBIV, revealing an interactional regulation of the two BldDs. In summary, our data indicated that the developmental regulator BldD played a vital role in directly regulating the biosynthesis of lincomycin, and expanded the knowledge on lincomycin biosynthetic regulation in S. lincolnensis.

TetR-Type Regulator SLCG_2919 Is a Negative Regulator of Lincomycin Biosynthesis in Streptomyces lincolnensis.

Lincomycin A (Lin-A) is a widely used antibacterial antibiotic fermented by Streptomyces lincolnensis However, the transcriptional regulatory mechanisms underlying lincomycin biosynthesis have seldom been investigated. Here, we first identified a TetR family transcriptional regulator (TFR), SLCG_2919, which negatively modulates lincomycin biosynthesis in S. lincolnensis LCGL. SLCG_2919 was found to specifically bind to promoter regions of the lincomycin biosynthetic gene cluster (lin cluster), including 25 structural genes, three resistance genes, and one regulatory gene, and to inhibit the transcription of these genes, demonstrating a directly regulatory role in lincomycin biosynthesis. Furthermore, we found that SLCG_2919 was not autoregulated, but directly repressed its adjacent gene, SLCG_2920, which encodes an ATP/GTP binding protein whose overexpression increased resistance against lincomycin and Lin-A yields in S. lincolnensis The precise SLCG_2919 binding site within the promoter region of SLCG_2920 was determined by a DNase I footprinting assay and by electrophoretic mobility shift assays (EMSAs) based on base substitution mutagenesis, with the internal 10-nucleotide (nt) AT-rich sequence (AAATTATTTA) shown to be essential for SLCG_2919 binding. Our findings indicate that SLCG_2919 is a negative regulator for controlling lincomycin biosynthesis in S. lincolnensis The present study improves our understanding of molecular regulation for lincomycin biosynthesis.IMPORTANCE TetR family transcriptional regulators (TFRs) are generally found to regulate diverse cellular processes in bacteria, especially antibiotic biosynthesis in Streptomyces species. However, knowledge of their function in lincomycin biosynthesis in S. lincolnensis remains unknown. The present study provides a new insight into the regulation of lincomycin biosynthesis through a TFR, SLCG_2919, that directly modulates lincomycin production and resistance. Intriguingly, SLCG_2919 and its adjoining gene, SLCG_2920, which encodes an ATP/GTP binding protein, were extensively distributed in diverse Streptomyces species. In addition, we revealed a new TFR binding motif, in which SLCG_2919 binds to the promoter region of SLCG_2920, dependent on the intervening AT-rich sequence rather than on the flanking inverted repeats found in the binding sites of other TFRs. These insights into transcriptional regulation of lincomycin biosynthesis by SLCG_2919 will be valuable in paving the way for genetic engineering of regulatory elements in Streptomyces species to improve antibiotic production.

Corrections to: Enhanced lincomycin production by co­overexpression of metK1 and metK2 in Streptomyces lincolnensis.

In the online published article, row value "pIB139-metK1-metK2" in table 1 has been processed incorrectly. The correct table is given below.

Enhanced lincomycin production by co-overexpression of metK1 and metK2 in Streptomyces lincolnensis.

Streptomyces lincolnensis is generally utilized for the production of lincomycin A (Lin-A), a clinically useful antibiotic to treat Gram-positive bacterial infections. Three methylation steps, catalyzed by three different S-adenosylmethionine (SAM)-dependent methyltransferases, are required in the biosynthesis of Lin-A, and thus highlight the significance of methyl group supply in lincomycin production. In this study, we demonstrate that externally supplemented SAM cannot be taken in by cells and therefore does not enhance Lin-A production. Furthermore, bioinformatics and in vitro enzymatic assays revealed there exist two SAM synthetase homologs, MetK1 (SLCG_1651) and MetK2 (SLCG_3830) in S. lincolnensis that could convert L-methionine into SAM in the presence of ATP. Even though we attempted to inactivate metK1 and metK2, only metK2 was deleted in S. lincolnensis LCGL, named as ΔmetK2. Following a reduction of the intracellular SAM concentration, ΔmetK2 mutant exhibited a significant decrease of Lin-A in comparison to its parental strain. Individual overexpression of metK1 or metK2 in S. lincolnensis LCGL either elevated the amount of intracellular SAM, concomitant with 15% and 22% increase in Lin-A production, respectively. qRT-PCR assays showed that overexpression of either metK1 or metK2 increased the transcription of lincomycin biosynthetic genes lmbA and lmbR, and regulatory gene lmbU, indicating SAM may also function as a transcriptional activator. When metK1 and metK2 were co-expressed, Lin-A production was increased by 27% in LCGL, while by 17% in a high-yield strain LA219X.