SYMBIOSIS: synthetic manipulable biobricks via orthogonal serine integrase systems.

Serine integrases are emerging as one of the most powerful biological tools for synthetic biology. They have been widely used across genome engineering and genetic circuit design. However, developing serine integrase-based tools for directly/precisely manipulating synthetic biobricks is still missing. Here, we report SYMBIOSIS, a versatile method that can robustly manipulate DNA parts in vivo and in vitro. First, we propose a 'keys match locks' model to demonstrate that three orthogonal serine integrases are able to irreversibly and stably switch on seven synthetic biobricks with high accuracy in vivo. Then, we demonstrate that purified integrases can facilitate the assembly of 'donor' and 'acceptor' plasmids in vitro to construct composite plasmids. Finally, we use SYMBIOSIS to assemble different chromoprotein genes and create novel colored Escherichia coli. We anticipate that our SYMBIOSIS strategy will accelerate synthetic biobrick manipulation, genetic circuit design and multiple plasmid assembly for synthetic biology with broad potential applications.

[Systematic review and sequential analysis of Tanshinone â ¡_A Sodium Sulfonate Injection combined with enalapril in treatment of acute exacerbation of pulmonary heart disease].

To systematically evaluate the clinical efficacy and safety of Tanshinone Ⅱ_A Sodium Sulfonate Injection combined with enalapril in the treatment of patients with acute exacerbation of pulmonary heart disease. The randomized controlled trial(RCT) on Tanshinone Ⅱ_A Sodium Sulfonate Injection combined with enalapril for acute exacerbation of pulmonary heart disease was screened from EMbase, PubMed, Web of Science, Cochrane Library, VIP, CNKI, and Wanfang from inception to March 20, 2022. Meta-analysis of each index was performed in RevMan 5.3 and TSA 0.9. Finally, 41 RCTs involving 3 865 patients were included. Meta-analysis showed that the observation group had higher total response rate(RR=1.21, 95%CI[1.18, 1.24], P<0.000 01), lower plasma viscosity(MD=-0.25, 95%CI[-0.34,-0.16], P<0.000 01), lower whole blood viscosity(MD=-0.99, 95%CI[-1.14,-0.85], P<0.000 01), and lower hematokrit(MD=-9.03, 95%CI[-10.57,-7.50], P<0.000 01) than the control group. The incidence of adverse effects showed no significant difference between groups(RR=1.42, 95%CI[0.82, 2.45], P=0.21). Sequential analysis showed that Tanshinone Ⅱ_A Sodium Sulfonate Injection combined with enalapril exerted definite efficacy in the treatment of acute exacerbation of pulmonary heart disease, and the possibility of false positives was excluded. Based on the existing evidence, Tanshinone Ⅱ_A Sodium Sulfonate Injection combined with enalapril can improve the total response rate and reduce plasma viscosity, whole blood viscosity, and hematocrit, demonstrating good safety in patients with acute exacerbation of pulmonary heart disease. In the future, more RCT with large sample size, rigorous design, and in accordance with international norms are needed to further validate the results.

Regulatory Part Engineering for High-Yield Protein Synthesis in an All-Streptomyces-Based Cell-Free Expression System.

Streptomyces-based cell-free expression systems have been developed to meet the demand for synthetic biology applications. However, protein yields from the previous Streptomyces systems are relatively low, and there is a serious limitation of available genetic tools such as plasmids for gene (co)expression. Here, we sought to expand the plasmid toolkit with a focus on the enhancement of protein production. By screening native promoters and ribosome binding sites, we were able to construct a panel of plasmids with different abilities for protein synthesis, which covered a nearly 3-fold range of protein yields. Using the most efficient plasmid, the protein yield reached up to a maximum value of 515.7 ± 25.3 µg/mL. With the plasmid toolkit, we anticipate that our Streptomyces cell-free system will offer great opportunities for cell-free synthetic biology applications such as in vitro biosynthesis of valuable natural products when cell-based systems remain difficult or not amenable.

Cell-free expression of NO synthase and P450 enzyme for the biosynthesis of an unnatural amino acid L-4-nitrotryptophan.

Cell-free system has emerged as a powerful platform with a wide range of in vitro applications and recently has contributed to express metabolic pathways for biosynthesis. Here we report in vitro construction of a native biosynthetic pathway for L-4-nitrotryptophan (L-4-nitro-Trp) synthesis using an Escherichia coli-based cell-free protein synthesis (CFPS) system. Naturally, a nitric oxide (NO) synthase (TxtD) and a cytochrome P450 enzyme (TxtE) are responsible for synthesizing L-4-nitro-Trp, which serves as one substrate for the biosynthesis of a nonribosomal peptide herbicide thaxtomin A. Recombinant coexpression of TxtD and TxtE in a heterologous host like E. coli for L-4-nitro-Trp production has not been achieved so far due to the poor or insoluble expression of TxtD. Using CFPS, TxtD and TxtE were successfully expressed in vitro, enabling the formation of L-4-nitro-Trp. After optimization, the cell-free system was able to synthesize approximately 360 µM L-4-nitro-Trp within 16 h. Overall, this work expands the application scope of CFPS for study and synthesis of nitro-containing compounds, which are important building blocks widely used in pharmaceuticals, agrochemicals, and industrial chemicals.

Permeability-Engineered Compartmentalization Enables In Vitro Reconstitution of Sustained Synthetic Biology Systems.

In nature, biological compartments such as cells rely on dynamically controlled permeability for matter exchange and complex cellular activities. Likewise, the ability to engineer compartment permeability is crucial for in vitro systems to gain sustainability, robustness, and complexity. However, rendering in vitro compartments such a capability is challenging. Here, a facile strategy is presented to build permeability-configurable compartments, and marked advantages of such compartmentalization are shown in reconstituting sustained synthetic biology systems in vitro. Through microfluidics, the strategy produces micrometer-sized layered microgels whose shell layer serves as a sieving structure for biomolecules and particles. In this configuration, the transport of DNAs, proteins, and bacteriophages across the compartments can be controlled an guided by a physical model. Through permeability engineering, a compartmentalized cell-free protein synthesis system sustains multicycle protein production; ≈100 000 compartments are repeatedly used in a five-cycle synthesis, featuring a yield of 2.2 mg mL-1 . Further, the engineered bacteria-enclosing compartments possess near-perfect phage resistance and enhanced environmental fitness. In a complex river silt environment, compartmentalized whole-cell biosensors show maintained activity throughout the 32 h pollutant monitoring. It is anticipated that permeability-engineered compartmentalization should pave the way for practical synthetic biology applications such as green bioproduction, environmental sensing, and bacteria-based therapeutics.

A Polyvinyl Alcohol-Tannic Acid Gel with Exceptional Mechanical Properties and Ultraviolet Resistance.

Design and preparation of gels with excellent mechanical properties has garnered wide interest at present. In this paper, preparation of polyvinyl alcohol (PVA)-tannic acid (TA) gels with exceptional properties is documented. The crystallization zone and hydrogen bonding acted as physical crosslinkages fabricated by a combination of freeze-thaw treatment and a tannic acid compound. The effect of tannic acid on mechanical properties of prepared PVA-TA gels was investigated and analyzed. When the mass fraction of PVA was 20.0 wt% and soaking time was 12 h in tannic acid aqueous solution, tensile strength and the elongation at break of PVA-TA gel reached 5.97 MPa and 1450%, respectively. This PVA-TA gel was far superior to a pure 20.0 wt% PVA hydrogel treated only with the freeze-thaw process, as well as most previously reported PVA-TA gels. The toughness of a PVA-TA gel is about 14 times that of a pure PVA gel. In addition, transparent PVA-TA gels can effectively prevent ultraviolet-light-induced degradation. This study provides a novel strategy and reference for design and preparation of high-performance gels that are promising for practical application.