Biotechnology Journal最新文献

Pro-viral Insertion site for the Moloney Murine Leukemia virus 1 (PIM-1) is widely involved in various biological processes and diseases, which is based on its structure and functional sites. However, the relationship between active sites and function of PIM-1 kinase remains unclear due to the lack of effective study approaches in live cells. Herein, to visualize the effect of different active sites in PIM-1 protein on its function activity and relation with PI3K/Akt/mTOR pathway, three mutant probes of EPHY which was developed previously based on fluorescence resonance energy transfer (FRET) technology to detect PIM-1 kinase activity in living cells were further constructed and transfected into cells followed by treating with PIM-1 inhibitors, ATP and PI3K inhibitor, respectively. The results showed that Lys67 is related to substrate binding and catalytic activity of PIM-1 kinase, thereby directly regulating PI3K/Akt/mTOR signaling pathway. Pro81/Asn82 are primarily participated in PIM-1 binding to ATP, thus also involving in the modulation on PI3K/Akt/mTOR signaling pathway, but play less role in the interaction between PIM-1 protein and its substrate. Asp167 has few effects on both the catalytic function activity of PIM-1 and PI3K/AKT/mTOR pathway, even though the binding ability of PIM-1 protein to its substrate is dramatically inhibited by D167A mutation. Altogether, the mutant probes works well as visualization tools to unearth the function of active sites in PIM-1 kinase, not only facilitating the further clarification of molecular mechanism underlying PIM-1 related signaling pathways, but also shedding light on drug development and disease therapy targeting PIM-1 protein.

Hydrophobic feedstocks such as waste cooking oil have recently been considered for microbial biotransformation due to their abundance, low cost, and unique advantage for lipid-derived fermentation products. Most fermentations with hydrophobic substrates are conducted at the tube or flask scale (less than 1 L total volume) or with the hydrophobic substrate comprising a small fraction of the media. Low substrate concentrations require additional feeding. Alternatively, high concentrations do not require significant dilution of the oil feedstock, which reduce volumetric requirements for larger scale fermentations. However, high-oil-density fermentations complicate efficient mixing and mass transfer challenges which are exacerbated at larger scales. To address this, computational fluid dynamics (CFD) models were explored to simulate three-phase (hydrophobic, hydrophilic, and gaseous) bench (3 L) and pilot scale (4000 L) bioreactors, highlighting challenges and potential considerations. Bioreactor fermentations of Yarrowia lipolytica strain L36DGA1 with substrate loadings of 5%, 10%, 20%, 30%, 40%, and 50% (v/v) waste cooking oil were also conducted, representing one of the highest concentrations in the reported literature. This work supports future research into and implementation of high-oil-density fermentations at the bench and pilot bioreactor scale.

When constructing cell factories, it is crucial to reallocate intracellular resources towards the synthesis of target compounds. However, imbalanced resource allocation can lead to a tradeoff between cell growth and production, reducing overall efficiency. Reliable gene expression regulation tools are needed to coordinate cell growth and production effectively. The orthogonal translation system, developed based on genetic code expansion (GCE), incorporates non-canonical amino acids (ncAAs) into proteins by assigning them to expanded codons, which enables the control of target protein expression at the translational level in an ncAA-dependent manner. However, the stringency of this regulatory tool remains inadequate. This study achieved strict translational-level control of the orthogonal translation system by addressing the abnormal leakage caused by the arabinose-inducible promoter. Further validation was conducted on the relationship between ncAA concentration and expression level, as well as the host's adaptability to the system. Subsequently, the system's applicability across multiple Escherichia coli hosts was verified by examining the roles of RF1 (peptide chain release factor 1) and endogenous TAG codons. By combining this strategy with inducible promoters, dual-level regulation of target gene expression at both transcriptional and translational levels was achieved and the dynamic range was further increased to over 20-fold. When using ncAA to control the expression of T7 RNA polymerase (T7 RNAP), the leakage expression was reduced by 82.7%, mitigating the low production efficiency caused by extensive leakage in the T7 system. As proof of concept, the strategy enhanced the production of alcohol dehydrogenase (ADH) by 9.82-fold, demonstrating its excellent capability in controlling gene expression in developing cell factories.

Saccharomyces boulardii, as a probiotic yeast, has shown great potential in regulating gut health and treating gastrointestinal diseases. Due to its unique antimicrobial and immune-regulating functions, it has become a significant subject of research in the field of probiotics. In this study, we aim to enhance the antioxidant properties of S. boulardii by producing l-ergothioneine (EGT). We first constructed a double knockout of ura3 and trp1 gene in S. boulardii to facilitate plasmid-based expressions. To further enable effective genome editing of S. boulardii, we implemented the PiggyBac system to transpose the heterologous gene expression cassettes into the chromosomes of S. boulardii. By using enhanced green fluorescent protein (EGFP) as the reporter gene, we achieved random chromosomal integration of EGFP expression cassette. By using PiggyBac transposon system, a great variety of EGT-producing strains was obtained, which is not possible for the conventional single target genome editing, and one best isolated top producer reached 17.50 mg/L EGT after 120 h cultivation. In summary, we have applied the PiggyBac transposon system to S. boulardii for the first time for genetic engineering. The engineered probiotic yeast S. boulardii has been endowed with new antioxidant properties and produces EGT. It has potential applications in developing novel therapeutics and dietary supplements for the prevention and treatment of gastrointestinal disorders.

Boldenone (BD), a protein anabolic hormone, is commonly used to treat muscle damage, osteoporosis, and off-season muscle building in athletes. Traditional BD synthesis methods rely on chemical processes, which are costly and environmentally impactful. Therefore, developing a more sustainable and economical biosynthetic pathway is crucial for BD production. This study aimed to achieve efficient production of BD. Firstly, the catalytic performance of 17β-hydroxysteroid dehydrogenase and 3-ketosteroid-Δ¹-dehydrogenase was improved through enzyme engineering, and their expression in the new strain of Mycobacterium neoaurum was enhanced using metabolic engineering. These improvements significantly increased BD production to 4.05 g/L, with a significant decrease in by-product generation. To further increase the yield, a multi-enzyme fusion expression system was constructed, and a key cell wall gene kasB was knocked out, resulting in a spatial-time yield of BD reaching 1.02 g/(L·d). Subsequent optimization of the transformation system further increased the BD production to 5.56 g/L, with a spatiotemporal yield of 1.39 g/(L·d). The green biosynthetic route of phytosterol one-step conversion to BD developed in this study lays the foundation for industrial production.