Construction of a Tandem Repeat Peptide Sequence with Pepsin Cutting Sites to Produce Recombinant α-Melanocyte-Stimulating Hormone

Heterologous expression of a recombinant ACE inhibitory peptide LYPVK and its potential antihypertensive action mechanism

Enzymatic hydrolysis approach is commonly employed for preparation of active peptides, while the limited purity and yield of produced peptides hinder further development of action mechanisms. This study presents the biotechnological approach for the efficient production of recombinant angiotensin converting enzyme (ACE) inhibitory peptide LYPVK and investigates its potential antihypertensive action mechanism. DNA encoding sequence of recombinant peptide was designed to form in tandem, which was expressed in Escherichia coli BL21 (DE3). The expressed tandem repeat protein with molecular weight of 13.4 kDa was verified by high performance liquid chromatography (HPLC) and amino acid composition. Subsequently, LYPVK was generated following His-tag removal and trypsin-mediated cleavage of the purified protein, which was performed HPLC and liquid chromatography-mass spectrometry (LC-MS) analysis. LYPVK exhibited an IC50 value of 10.6 ± 0.86 μg/mL, demonstrating a non-competitive mode of action and resistance to gastrointestinal enzyme hydrolysis and heat conditions. Molecular docking results showed that LYPVK interacted with ACE through conventional hydrogen bonds and hydrophobic interactions. Except for ACE, ALB, SRC, PPARG, and MMP9 are identified as potential key targets for its antihypertensive activity by network pharmacological analysis. This study provides a promising biotechnological approach for the preparation of active peptides with high purity and yield.

Development of therapeutic peptide producers based on Escherichia coli BL21 and their cultivation technology

Introduction. Peptides with a molecular weight of less than 5 kDa have been used in medicine and biotechnology over the past decade for the treatment of various diseases. However, chemical synthesis peptide has several disadvantages, including low yield, reduced efficiency, and high costs. An alternative approach to peptide production is the use of the Escherichia coli expression system. The development of effective peptide synthesis technology remains a critical task because of the low productivity of recombinant strains.

Aim. Developing highly efficient strains of Escherichia coli BL21 expressing therapeutic peptides with a molecular weight of less than 5 kDa in E. coli and their cultivation technology.

Materials and methods. Genetic constructs were obtained using the restriction-ligase method, and their authenticity was confirmed by Sanger sequencing. Cultivation technology was developed using the Design of Experiments approach. The cultivation condition was validated in the Biostat B bioreactor. Hybrid proteins were purified by metal-chelate chromatography, followed by hydrolysis ULP proteas to obtain the target peptides. The quantitative content of the target protein was determined by capillary electrophoresis, and the authenticity of the protein was confirmed by HPLC-MS and ELISA.

Results and discussion. Highly efficient peptide-producing strains were developed. Cultivation conditions were optimized: рН 7.5 ± 0.5, cultivation temperature 37 °C, induction optical density 28 ± 2, IPTG concentration 0.05 мМ. The productivity of the producer strains was up to 4.82 ± 0.05 g/L. Furthermore, samples of the target peptides were isolated and purified.

Conclusion. The productivity of peptides in this study were significantly higher than in previous research. The presented strategy for strain development, cultivation and purification technology can be used production of therapeutic peptides with diverse physical chemicals characteristics in the future.

A Lambda-evo (λevo) phage platform for Zika virus EDIII protein display

One of the most significant bacteriophage technologies is phage display, in which heterologous peptides are exhibited on the virion surface. This work describes the display of λ decorative protein Dλ linked to the E protein domain III of Zika virus (Dλ-ZEDIII), to the GFP protein (Dλ-GFP), or to different domain III epitopes of the EZIKV protein (Dλ-TD), exhibited on the surface of an in vitro evolved lambda phage (λevo). This phage harbors a gene D deletion and was subjected to directed evolution using Escherichia coli W3110/pDλ-ZEDIII as background. After 20 days (20 cycles of dilution), the λevo phage developed a ~ 22% genome deletion affecting the non-essential λ b region, rendering a more stable phage that exhibited fusion proteins Dλ-ZEDIII or Dλ-GFP but not Dλ-TD. Despite the λevo system was able to decorate itself with the Dλ-ZEDIII protein, the production of viral particles was ~ 1000-fold lower than the λ wild-type, due to the unexpected Dλ-ZEDIII protein aggregation into bacterial inclusion bodies. Decorated phages (106 PFU (plaque forming units)/100 µl) were inoculated into BALB/c mice, and subsequent dot blot and Western blot immunoassays proved the production of murine antibodies against ZIKV (Zika virus). This multipurpose λevo phage display platform may be used interchangeably with other more soluble peptides, providing better yields. KEY POINTS: • λevo platform for displaying recombinant peptides. • Directed evolution to generate λevo with more efficient decoration. • Antigenic reaction in BALB/c mice by inoculating λevo with recombinant peptides.