Optimization of EnBase Fed-Batch Cultivation to Improve Soluble Fraction Ratio of α-Luffin Ribosome Inactivating Protein

In-silico analysis of ribosome inactivating protein (RIP) of the Cucurbitaceae family

Ribosome-inactivating proteins (RIPs) are highly active N-glycosidases that depurinate both bacterial and eukaryotic rRNAs, halting protein synthesis during translation. Found in a diverse spectrum of plant species and tissues, RIPs possess antifungal, antibacterial, antiviral, and insecticidal properties linked to plant defense. In this study, we investigated the physiochemical properties of RIP peptides from the Cucurbitaceae family through bioinformatics approaches. Molecular weight, isoelectric point, aliphatic index, extinction coefficient, and secondary structures were analyzed, revealing their hydrophobic nature. The novelty of this work lies in the comprehensive examination of RIPs from the Cucurbitaceae family and their potential therapeutic applications. The study also elucidated the binding interactions of Cucurbitaceae RIPs with key biological targets, including Interleukin-6 (IL-6). Strong hydrogen bond interactions between RIPs and these targets suggest potential for innovative insilico drug design and therapeutic applications, particularly in cancer treatment. Comprehensive analysis of bond lengths using Ligpolt + software provides insights for optimizing molecular interactions, offering a valuable tool for drug design and structural biology studies.

Recombinant anti-human epidermal growth factor receptor type 2 single-chain variable fragment-alpha-luffin fusion protein as a putative immunotoxin against human epidermal growth factor receptor type 2-positive breast cancer cells: an experimental research

Background

Breast cancer is one of the most frequent causes of cancer death in women. The application of immunotoxins to target overexpressed biomarkers on the surface of cancer cells and delivery of the toxin molecules into these cells has attracted too much attention during the last decade.

Objectives

This study was conducted to investigate the possible in-vitro cytotoxic and apoptotic activity of previously designed recombinant immunotoxin compromising anti-HER2 single-chain variable fragment (scFv) and alpha-luffin protein in human epidermal growth factor receptor type 2 (HER2)-positive and HER2-negative breast cancer cell lines.

Materials and methods

The previously designed recombinant immunotoxin and alpha-luffin protein were expressed in E. coli host cells and purified using Ni-affinity chromatography. The cytotoxicity of the proteins was tested through MTT and apoptosis studies on HER2-positive and HER2-negative breast cancer cell lines.

Results

Treatment of SKBR3 and MDA-MB-468 cells with the immunotoxin caused differential cytotoxicity and apoptotic events. Flow cytometry analysis indicated that the immunotoxin could arrest SKBR3 cells at the G0/G1 phase and induce apoptosis and cell death which were not observed in HER2-negative MDA-MB-468 cells. Annexin V/PI staining revealed late apoptotic events in SKBR3 cells treated with the immunotoxin which was different from the early apoptosis induced by the alpha-luffin protein alone.

Conclusions

This immunotoxin could be a promising tool in developing new targeted therapeutic agents against HER2-positive cancer cells. Animal experiments are needed before making firmed conclusions.

Production of an Antibody Fragment (scFv) Targeting PcrV Protein of Pseudomonas aeruginosa in Fed-Batch Cultivation Mode

Background:

Pseudomonas aeruginosa is one of the opportunistic pathogens causing frequent hospital-acquired life-threatening infections in mechanically ventilated patients. The most significant virulence factor of P. aeruginosa is T3SS. PcrV is an important structural protein of the T3SS.

Methods:

In the current investigation, a recombinant scFv mAb against the PcrV protein was expressed in EnBase® (fed-batch) cultivation mode. The pETiteTM N-His SUMO Kan vector, including anti-PcrV scFv gene, was transformed into Escherichia coli (BL21) cells. The expression and solubility of anti-PcrV scFv protein were investigated at two different temperatures (25 °C and 30 °C) and at different induction times (4, 6, 8, 12, and 24 hours).

Results:

Increased efficiency was achieved by EnBase® compared to LB broth; owing to the slow release of glucose, the maximum level of solubility and total protein expression was observed in EnBase® cultivation system at 30 °C and 24 h post induction. Furthermore, IC₅₀ for anti-PcrV scFv protein was determined to be approximately 7 μg/mL.

Conclusion:

Anti-PcrV scFv produced in this study showed promising in vitro results, protecting RBC from lysis by P. aeruginosa (exoU+).

Cloning, expression and characterization of a HER2-alpha luffin fusion protein in Escherichia coli

In recent decades, immunotoxins have attracted significant attention in treatment of a wide range of diseases including cancers due to their natural origins and their role in blocking crucial pathways within the cells. Ribosome inactivating proteins (RIPs) are efficient molecules in blocking protein synthesis through interactions with ribosomal rRNA molecules. cDNA molecule encoding HER2 scFv antibody fragment originated from trastuzumab attached to the mature alpha luffin gene fragment was subcloned into pET28a expression vector and expressed in different E. coli expression hosts. Identity of the expressed recombinant protein was investigated through western blotting and the fusion protein was purified using Ni-NTA affinity chromatography. The biological activity (toxicity) of the protein was investigated on DNA and RNA samples. A 58 kDa protein was expressed in E. coli. The best protein expression level was achieved in 0.2 mM IPTG at 30 °C in TB medium using E. coli BL21 (DE3) host strain. The fusion protein showed RNase and DNA glycosylase activity on tested RNA and DNA samples. DNA glycosylase activity of the recombinant fusion protein showed that alpha luffin part of this protein is active in conjugation to the scFv molecule and the expressed protein can be further studied in targeted biological in vitro assays.