Cost-Effective Production of ATP and S-Adenosylmethionine Using Engineered Multidomain Scaffold Proteins

β-glucans, SAM, and GSH fluctuations in barley anther tissue culture conditions affect regenerants' DNA methylation and GPRE

BACKGROUND

Microspore embryogenesis is a process that produces doubled haploids in tissue culture environments and is widely used in cereal plants. The efficient production of green regenerants requires stresses that could be sensed at the level of glycolysis, followed by the Krebs cycle and electron transfer chain. The latter can be affected by Cu(II) ion concentration in the induction media acting as cofactors of biochemical reactions, indirectly influencing the production of glutathione (GSH) and S-adenosyl-L-methionine (SAM) and thereby affecting epigenetic mechanisms involving DNA methylation (demethylation-DM, de novo methylation-DNM). The conclusions mentioned were acquired from research on triticale regenerants, but there is no similar research on barley. In this way, the study looks at how DNM, DM, Cu(II), SAM, GSH, and β-glucan affect the ability of green plant regeneration efficiency (GPRE).

RESULTS

The experiment involved spring barley regenerants obtained through anther culture. Nine variants (trials) of induction media were created by adding copper (CuSO4: 0.1; 5; 10 µM) and silver salts (AgNO3: 0; 10; 60 µM), with varying incubation times for the anthers (21, 28, and 35 days). Changes in DNA methylation were estimated using the DArTseqMet molecular marker method, which also detects cytosine methylation. Phenotype variability in β-glucans, SAM and GSH induced by the nutrient treatments was assessed using tentative assignments based on the Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The effectiveness of green plant regeneration ranged from 0.1 to 2.91 plants per 100 plated anthers. The level of demethylation ranged from 7.61 to 32.29, while de novo methylation reached values ranging from 6.83 to 32.27. The paper demonstrates that the samples from specific in vitro conditions (trials) formed tight groups linked to the factors contributing to the two main components responsible for 55.05% of the variance (to the first component DNM, DM, to the second component GSH, β-glucans, Cu(II), GPRE).

CONCLUSIONS

We can conclude that in vitro tissue culture conditions affect biochemical levels, DNA methylation changes, and GPRE. Increasing Cu(II) concentration in the IM impacts the metabolism and DNA methylation, elevating GPRE. Thus, changing Cu(II) concentration in the IM is fair to expect to boost GPRE.

Engineering of Methionine Adenosyltransferase toward Mitigated Product Inhibition for Efficient Production of S-Adenosylmethionine

S-Adenosylmethionine (SAM) is a crucial metabolic intermediate playing irreplaceable roles in organismal activities. However, the synthesis of SAM by methionine adenosyltransferase (MAT) is hindered by low conversion due to severe product inhibition. Herein structure-guided semirational engineering was conducted on MAT from Escherichia coli (EcMAT) to mitigate the product inhibitory effect. Compared with the wild-type EcMAT, the best variant E56Q/Q105R exhibited an 8.13-fold increase in half maximal inhibitory concentration and a 4.46-fold increase in conversion (150 mM ATP and l-methionine), leading to a SAM titer of 47.02 g/L. Another variant, E56N/Q105R, showed superior thermostability with an impressive 85.30-fold increase in half-life (50 °C) value. Furthermore, molecular dynamics (MD) simulation results demonstrate that the alleviation in product inhibitory effect could be attributed to facilitated product release. This study offers molecular insights into the mitigated product inhibition, and provides valuable guidance for engineering MAT toward enhanced catalytic performance.

Early-life exposures and the microbiome: implications for IBD prevention

The early-life period is one of microbiome establishment and immune maturation. Early-life exposures are increasingly being recognised to play an important role in IBD risk. The composition of functions of the gut microbiome in the prenatal, perinatal, and postnatal period may be crucial towards development of health or disease, including IBD, later in life. We herein present a comprehensive summary of the interplay between early-life factors and microbiome perturbations, and their association with risk of IBD. In addition, we provide an overview of host and external factors in early life that are known to impact gut microbiome maturation and exposures implicated in IBD risk. Considering the emerging concept of IBD prevention, we propose strategies to minimise maternal and offspring exposure to potentially harmful variables and recommend protective measures during pregnancy and the postpartum period. This holistic view of early-life factors and microbiome signatures among mothers and their offspring will help frame our current understanding of their importance towards IBD pathogenesis and frame the roadmap for preventive strategies.

Improving ATP availability by sod1 deletion with a strategy of precursor feeding enhanced S-adenosyl-L-methionine accumulation in Saccharomyces cerevisiae

S-adenosyl-L-methionine (SAM), used in diverse pharmaceutical applications, was biosynthesized from L-methionine (L-met) and adenosine triphosphate (ATP). This study aims to increase the accumulation of SAM in Saccharomyces cerevisiae by promoting ATP availability. Strain ΔSOD1 was obtained from the parent strain WT15-33 (CCTCC M 2021915) by deleting gene sod1, which improved the supply of ATP. The SAM content in strain ΔSOD1 exhibited a 22.3% improvement compared to the parent strain, which reached 93.6 mg g^-1. The transformation of NADH (reduced nicotinamide adenine dinucleotide) and the relative expression of ATPase essential genes were investigated, respectively. The results showed that the lack of gene sod1 benefited the generation of ATP, which positively regulated the synthesis of SAM. Besides that, the production of SAM was further enhanced by improving substrate assimilation. With the infusion of 1.44 g L^-1L-met and 0.60 g L^-1 adenosine at 24 h (h) and 0 h following fermentation, the optimum medium could produce 1.54 g L^-1 SAM. Based on the regulations mentioned above, the SAM concentration of strain ΔSOD1 enhanced from 7.3 g L^-1 to 10.1 g L^-1 in a 5-L fermenter in 118 h. This work introduces a novel idea for the biosynthesis of ATP and SAM, and the strain ΔSOD1 has the potential for industrial production.

Development of a synthetic transcription factor-based S-adenosylmethionine biosensor in Saccharomyces cerevisiae

S-Adenosylmethionine (SAM) is a crucial small-molecule metabolite widely used in food and medicine. The development of high-throughput biosensors for SAM biosynthesis can significantly improve the titer of SAM. This paper constructed a synthetic transcription factor (TF)-based biosensor for SAM detecting in Saccharomyces cerevisiae. The synthetic TF, named MetJ-hER-VP16, consists of an Escherichia coli-derived DNA-binding domain MetJ, GS linker, the human estrogen receptor binding domain hER, and the viral activation domain VP16. The synthetic biosensor is capable of sensing SAM in a dose-dependent manner with fluorescence as the output. Additionally, it is tightly regulated by the inducer SAM and β-estradiol, which means that the fluorescence output is only available when both are present together. The synthetic SAM biosensor could potentially be applied for high-throughput metabolic engineering and is expected to improve SAM production.

Metabolomic Changes as Key Factors of Green Plant Regeneration Efficiency of Triticale In Vitro Anther Culture

Green plant regeneration efficiency (GPRE) via in vitro anther culture results from biochemical pathways and cycle dysfunctions that may affect DNA and histone methylation, with gene expression influencing whole cell functioning. The reprogramming from gametophytic to sporophytic fate is part of the phenomenon. While DNA methylation and sequence changes related to the GPRE have been described, little attention was paid to the biochemical aspects of the phenomenon. Furthermore, only a few theoretical models that describe the complex relationships between biochemical aspects of GPRE and the role of Cu(II) ions in the induction medium and as cofactors of enzymatic reactions have been developed. Still, none of these models are devoted directly to the biochemical level. Fourier transform infrared (FTIR) spectroscopy was used in the current study to analyze triticale regenerants derived under various in vitro tissue culture conditions, including different Cu(II) and Ag(I) ion concentrations in the induction medium and anther culture times. The FTIR spectra of S-adenosyl-L-methionine (SAM), glutathione, and pectins in parallel with the Cu(II) ions, as well as the evaluated GPRE values, were put into the structural equation model (SEM). The data demonstrate the relationships between SAM, glutathione, pectins, and Cu(II) in the induction medium and how they affect GPRE. The SEM reflects the cell functioning under in vitro conditions and varying Cu(II) concentrations. In the presented model, the players are the Krebs and Yang cycles, the transsulfuration pathway controlled by Cu(II) ions acting as cofactors of enzymatic reactions, and the pectins of the primary cell wall.

Whole-Cell Display of Phosphotransferase in Escherichia coli for High-Efficiency Extracellular ATP Production

Adenosine triphosphate (ATP), as a universal energy currency, takes a central role in many biochemical reactions with potential for the synthesis of numerous high-value products. However, the high cost of ATP limits industrial ATP-dependent enzyme-catalyzed reactions. Here, we investigated the effect of cell-surface display of phosphotransferase on ATP regeneration in recombinant Escherichia coli. By N-terminal fusion of the super-folder green fluorescent protein (sfGFP), we successfully displayed the phosphotransferase of Pseudomonas brassicacearum (PAP-Pb) on the surface of E. coli cells. The catalytic activity of sfGFP-PAP-Pb intact cells was 2.12 and 1.47 times higher than that of PAP-Pb intact cells, when the substrate was AMP and ADP, respectively. The conversion of ATP from AMP or ADP were up to 97.5% and 80.1% respectively when catalyzed by the surface-displayed enzyme at 37 °C for only 20 min. The whole-cell catalyst was very stable, and the enzyme activity of the whole cell was maintained above 40% after 40 rounds of recovery. Under this condition, 49.01 mg/mL (96.66 mM) ATP was accumulated for multi-rounds reaction. This ATP regeneration system has the characteristics of low cost, long lifetime, flexible compatibility, and great robustness.