Simultaneously achieve soluble expression and biomimetic immobilization of Candida antarctica lipase B by introducing polyamine tags

Engineering silica encapsulated composite of acyltransferase from Mycobacterium smegmatis and MIL-88A: A stability-and activity-improved biocatalyst for N-acylation reactions in water

Here the metal-organic framework material MIL-88A is used to purify and immobilize an acyltransferase from Mycobacterium smegmatis (MsAcT) simultaneously from the broken bacterial liquid. Regarding the possibility that the MsAcT@MIL-88A may display weak stability in its application, a silica layer is further introduced around it as a "shield" to protect the enzyme from degradation. The obtained MsAcT@MIL-88A@silica can exhibit high activity recovery, excellent thermal, pH, and storage stabilities compared with those of MsAcT@MIL-88A. The MsAcT@MIL-88A@silica can also be effectively recycled, and its initial activity of 84.0 % ± 1.2 % can be retained after the 5th cycle for N-acylation reaction in water. More importantly, the MsAcT@MIL-88A@silica can display much higher catalytic activity towards the reactions between ethyl or vinyl esters and aniline than those of free MsAcT and MsAcT@MIL-88A in aqueous media. This study provides a simple and inexpensive strategy to prepare MsAcT@MIL-88A@silica with high activity, stability, and excellent recyclability, and highlights its application potential as a biocatalyst.

A novel protein fusion partner, carbohydrate-binding module family 66, to enhance heterologous protein expression in Escherichia coli

Background

Proteins with novel functions or advanced activities developed by various protein engineering techniques must have sufficient solubility to retain their bioactivity. However, inactive protein aggregates are frequently produced during heterologous protein expression in Escherichia coli. To prevent the formation of inclusion bodies, fusion tag technology has been commonly employed, owing to its good performance in soluble expression of target proteins, ease of application, and purification feasibility. Thus, researchers have continuously developed novel fusion tags to expand the expression capacity of high-value proteins in E. coli.

Results

A novel fusion tag comprising carbohydrate-binding module 66 (CBM66) was developed for the soluble expression of heterologous proteins in E. coli. The target protein solubilization capacity of the CBM66 tag was verified using seven proteins that are poorly expressed or form inclusion bodies in E. coli: four human-derived signaling polypeptides and three microbial enzymes. Compared to native proteins, CBM66-fused proteins exhibited improved solubility and high production titer. The protein-solubilizing effect of the CBM66 tag was compared with that of two commercial tags, maltose-binding protein and glutathione-S-transferase, using poly(ethylene terephthalate) hydrolase (PETase) as a model protein; CBM66 fusion resulted in a 3.7-fold higher expression amount of soluble PETase (approximately 370 mg/L) compared to fusion with the other commercial tags. The intact PETase was purified from the fusion protein upon serial treatment with enterokinase and affinity chromatography using levan-agarose resin. The bioactivity of the three proteins assessed was maintained even when the CBM66 tag was fused.

Conclusions

The use of the CBM66 tag to improve soluble protein expression facilitates the easy and economic production of high-value proteins in E. coli.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-021-01725-w.

Rational enhancement of enzyme-catalyzed enantioselective reaction by construction of recombinant enzymes based on additive strategy

A rational enhancement of kinetic resolution process for producing (S)-N-(2-ethyl-6-methylphenyl) alanine from racemic methyl ester using lipase B from Candida antarctica (CalB) was investigated. With the benefit results that lipase CalB-catalyzed reactions can be effectively regulated using amino acids (such as histidine and lysine) as additives, CalBs modified (mCalBs) by n-histidines at the N terminal and n-lysines at the C terminal were constructed and expressed. The results show that both soluble and precipitated mCalBs can effectively catalyze the hydrolysis reaction without adding any extra additives. The enantioselective ratio (E value) of soluble and precipitated mCalBs could be improved from 12.1 to 20.3, which were higher than that (E value was only 10.2) of commercial Novozym 435 (immobilized CalB). The study indicated that the amino acid-rich molecules introduced on lipase CalB can produce positive effects on enantioselectivity of enzyme. It provides unusual ideas for reasonable regulation of enzyme-catalyzed reactions.

Programmable stimuli-responsive polypeptides for biomimetic synthesis of silica nanocomposites and enzyme self-immobilization

Bioinspired silicification is an attractive route for achieving unique silica nanocomposites. Herein, a novel, facile and inexpensive route for biosilica synthesis is developed using the stimuli-responsive elastin-like polypeptide (ELP). The ELP is precisely tailored to a silica-mineralizing peptide by programming it with lysine residues. The resulting cationic ELP[KV₈F-40] is purified in ultrahigh yield using a chromatography-free ITC purification technique based on thermal-responsive property. Excitingly, the specific activity of ELP is 40-fold higher than that of silaffin. Besides, efficient and strong entrapment of ELP is achieved with over 98% of immobilization yield and less than 2% of leakage. These imply that cationic ELP may be used as a bifunctional tag (purification and immobilization) for fusion protein. An enzyme (xylanase) is therefore chosen to genetically fuse to ELP. The ELP-fused xylanase is purified by ELP with high purity (~98%) and enables the rapid (within minutes) self-immobilization. The immobilization yield was greater than 95%, and the immobilized xylanases hardly leaked from the silica matrix, demonstrating high efficiency of the self-immobilization process. The strategy developed here may provide a new opportunity for fabricating functional silica nanocomposites in a feasible and inexpensive pathway, which will have great potentials in the field of biotechnology.

Directly covalent immobilization of Candida antarctica lipase B on oxidized aspen powder by introducing poly‑lysines: An economical approach to improve enzyme performance

In our previous study, we could achieve high soluble expression of Candida antarctica lipase B (CalB) in E. coli by fusion poly‑amino acid tags on CalB (pCalB). Herein, we are surprised to find that pCalB can be easily and directly covalent binding on a simply oxidized aspen powder (OAP) by the aid of poly‑lysine tags. Under the optimal conditions, 72.9 ± 3.6% of the total protein could be immobilized, and the activity recovery of immobilized pCalB (pCalB-OAP) was 98.9 ± 3.8%. The analysis of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) indicated that OAP was a suitable carrier for enzyme immobilization. The immobilized pCalB-OAP could exhibit excellent thermal stabilities, and it retained a residual activity of 58.4 ± 2.8% at 55 °C, whereas only 21.2 ± 2.2% of its initial activity for free pCalB was observed. And it could also display a nice tolerance for the changes of pH environment, compared with that of free pCalB. The results that pCalB-OAP could retained 73.6 ± 2.9% of their initial activity in (R, S)-NEMPAME hydrolysis after the tenth cycles, suggested that pCalB-OAP could be effectively recycled. The immobilization strategies established here were simple and inexpensive.