Overproduction of α-Lipoic Acid by Gene Manipulated Escherichia coli

Metabolome insights into nutrients and glucosinolates in broccoli and lacinato kale

To elucidate differences in nutritional components and glucosinolates between broccoli and lacinato kale leaves, and to promote consumption of broccoli and kale leaves for human nutrition, food development, and by-product utilisation, this study used UPLC-MS/MS and HPLC for both qualitative and quantitative analyses of their metabolome and glucosinolate profiles. In broccoli leaves, 11 glucosinolates were identified, notably including high concentrations of glucoraphanin, glucobrassicin, and neoglucobrassicin. In contrast, lacinato kale leaves contained seven glucosinolates, with glucoraphasatin being the most abundant. Moreover, our analysis revealed 644 metabolites, 87 of which were differentially expressed between these crucuiferous vegetables. These findings not only offer new insights into nutritional value but also highlight their potential as plant chassis for the biosynthesis of valuable products, thereby broadening food diversity and improving by-product utilisation.

STING directly interacts with PAR to promote apoptosis upon acute ionizing radiation-mediated DNA damage

Acute ionizing radiation (IR) causes severe DNA damage, leading to cell cycle arrest, cell death, and activation of the innate immune system. The role and signaling pathway of stimulator of interferon genes (STING) in IR-induced tissue damage and cell death are not well understood. This study revealed that STING is crucial for promoting apoptosis in response to DNA damage caused by acute IR both in vitro and in vivo. STING binds to poly (ADP‒ribose) (PAR) produced by activated poly (ADP‒ribose) polymerase-1 (PARP1) upon IR. Compared with that in WT cells, apoptosis was suppressed in Stinggt-/gt- cells. Excessive PAR production by PARP1 due to DNA damage enhances STING phosphorylation, and inhibiting PARP1 reduces cell apoptosis after IR. In vivo, IR-induced crypt cell death was significantly lower in Stinggt-/gt- mice or with low-dose PARP1 inhibitor, PJ34, resulting in substantial resistance to abdominal irradiation. STING deficiency or inhibition of PARP1 function can reduce the expression of the proapoptotic gene PUMA, decrease the localization of Bax on the mitochondrial membrane, and thus reduce cell apoptosis. Our findings highlight crucial roles for STING and PAR in the IR-mediated induction of apoptosis, which may have therapeutic implications for controlling radiation-induced apoptosis or acute radiation symptoms. STING responds to acute ionizing radiation-mediated DNA damage by directly binding to poly (ADP-ribose) (PAR) produced by activated poly (ADP-ribose) polymerase-1 (PARP1), and mainly induces cell apoptosis through Puma-Bax interaction. STING deficiency or reduced production of PAR protected mice against Acute Radiation Syndrome.

Comprehensive Analysis of blaCTX-M1 Gene Expression Alongside iutA, csgA, and kpsMII Virulence Genes in Septicemic Escherichia coli Using Real-Time PCR

Background: Sepsis is a serious worldwide health concern, and Escherichia coli (E. coli) is the main cause. This study investigates the co-expression of blaCTX-M1 and iutA, csgA, and kpsMII genes in E. coli isolated from septicemic patients, aiming to clarify the interaction between virulence and resistance. Methods: This study evaluated 100 E. coli isolates from septicemic patients. With the disc diffusion method, antibiotic susceptibility was confirmed. The use of ceftazidime-clavulanic acid allowed for the confirmation of ESBL. PCR and real-time PCR were used to detect virulence and beta-lactamase genes. The expression levels of important genes were compared between isolates in LB and blood. Results: Antibiotic resistance was common in isolates carrying blaCTX-M1, including tetracycline (93%) and erythromycin (99%). Instead, there was no resistance to fosfomycin and 3% resistance to carbapenems. Real-time PCR revealed more expression levels in blood for the virulence genes kpsMII and csgA. Pathogenicity and resistance increased with blaCTX-M1 co-expression with the kpsMII and csgA genes. Conclusions: The coexistence of ESBL and virulence genes in E. coli isolates significantly increases antibiotic resistance and infection severity. Monitoring of these genes is critical for developing effective therapeutic strategies. The key to treating these diseases is having sophisticated diagnostic tools and using antibiotics cautiously.

Escherichia Coli Increases its ATP Concentration in Weakly Acidic Environments Principally through the Glycolytic Pathway

Acid resistance is an intrinsic characteristic of intestinal bacteria in order to survive passage through the stomach. Adenosine triphosphate (ATP), the ubiquitous chemical used to power metabolic reactions, activate signaling cascades, and form precursors of nucleic acids, was also found to be associated with the survival of Escherichia coli (E. coli) in acidic environments. The metabolic pathway responsible for elevating the level of ATP inside these bacteria during acid adaptation has been unclear. E. coli uses several mechanisms of ATP production, including oxidative phosphorylation, glycolysis and the oxidation of organic compounds. To uncover which is primarily used during adaptation to acidic conditions, we broadly analyzed the levels of gene transcription of multiple E. coli metabolic pathway components. Our findings confirmed that the primary producers of ATP in E. coli undergoing mild acidic stress are the glycolytic enzymes Glk, PykF and Pgk, which are also essential for survival under markedly acidic conditions. By contrast, the transcription of genes related to oxidative phosphorylation was downregulated, despite it being the major producer of ATP in neutral pH environments.

Mechanism-Driven Metabolic Engineering for Bio-Based Production of Free R-Lipoic Acid in Saccharomyces cerevisiae Mitochondria

Lipoic acid is a valuable organosulfur compound used as an antioxidant for dietary supplementation, and potentially anti-diabetic and anti-cancer. Currently, lipoic acid is obtained mainly through chemical synthesis, which requires toxic reagents and organic solvents, thus causing environmental issues. Moreover, chemically synthesized lipoic acid is conventionally a racemic mixture. To obtain enantiomerically pure R-lipoic acid, which has superior bioactivity than the S form, chiral resolution and asymmetric synthesis methods require additional reagents and solvents, and often lead to wastage of S-lipoic acid or precursors with undesired chirality. Toward sustainable production of R-lipoic acid, we aim to develop a synthetic biology-based method using engineered yeast. Here, we deepened mechanistic understanding of lipoic acid biosynthesis and protein lipoylation in the model yeast Saccharomyces cerevisiae to facilitate metabolic engineering of the microbe for producing free R-lipoic acid. In brief, we studied the biosynthesis and confirmed the availability of protein-bound lipoate in yeast cells through LC-MS/MS. We then characterized in vitro the activity of a lipoamidase from Enterococcus faecalis for releasing free R-lipoic acid from lipoate-modified yeast proteins. Overexpression of the lipoamidase in yeast mitochondria enabled de novo free R-lipoic acid production in vivo. By overexpressing pathway enzymes and regenerating the cofactor, the production titer was increased ∼2.9-fold. This study represents the first report of free R-lipoic acid biosynthesis in S. cerevisiae. We envision that these results could provide insights into lipoic acid biosynthesis in eukaryotic cells and drive development of sustainable R-lipoic acid production.