Microbiology
Zahra Gholipour; Abbas Ali Imani Fooladi; Kazem Parivar; Raheleh Halabian
Abstract
Background & Objective: Superantigens are bacterial toxins that induce a massive immune response in the host. Superantigen staphylococcal enterotoxin B (SEB) can form a ternary complex with its receptors, MHC class II (MHCII) and TCR, and can be used in tumor-targeting therapy, particularly when ...
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Background & Objective: Superantigens are bacterial toxins that induce a massive immune response in the host. Superantigen staphylococcal enterotoxin B (SEB) can form a ternary complex with its receptors, MHC class II (MHCII) and TCR, and can be used in tumor-targeting therapy, particularly when cooperating with a specific vector. In this study, SEB was fused to interleukin-13 (IL13), which forms a complex with IL13 receptor α2 (IL13Rα2) overexpressed in glioblastoma multiforme (GBM) cells for therapeutic goals.
Methods We designed four fusion proteins based on the arrangement of SEB (N- or C-terminal domain) and provided a flexible inter-domain linker (no or yes), resulting in the formation of SEB-IL13, SEB-L-IL13, IL13-SEB, and IL13-L-SEB, respectively. These fusion proteins were then evaluated for their various physicochemical properties and structural characteristics. Bioinformatics tools were employed to predict, refine, and validate the three-dimensional structure of the fusion proteins. In addition, the fusion proteins were docked with IL13Rα2, MHCII, and TCR receptors through the HADDOCK 2.4 server. The candidate fusion protein was subjected to molecular dynamics simulation.
Results: There were differences among the designed fusion proteins. The model with the N-terminal domain of IL13 and containing an inter-domain linker (IL13-L-SEB) was stable and had a long half-life. The docking analysis revealed that the IL13-L-SEB fusion protein had a higher binding affinity to the IL13Rα2, MHCII, and TCR receptors. Finally, using molecular dynamics simulation through iMODS, acceptable results were obtained for the IL13-L-SEB docked complexes.
Conclusion: The results suggest IL13-L-SEB is a promising novel fusion protein for cancer therapeutic application.
Microbiology
Zeynab Mohseni Moghadam; Raheleh Halabian; Hamid Sedighian; Elham Behzadi; Jafar Amani; Abbas ali Imani fooladi
Abstract
Background & Objective: A main contest in chemotherapy is to obtain regulator above the biodistribution of cytotoxic drugs. The utmost promising strategy comprises of drugs coupled with a tumor-targeting bearer that results in wide cytotoxic activity and particular delivery. The B-subunit of Shiga ...
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Background & Objective: A main contest in chemotherapy is to obtain regulator above the biodistribution of cytotoxic drugs. The utmost promising strategy comprises of drugs coupled with a tumor-targeting bearer that results in wide cytotoxic activity and particular delivery. The B-subunit of Shiga toxin (STxB) is nontoxic and possesses low immunogenicity that exactly binds to the globotriaosylceramide (Gb3/CD77). Gb3/CD77 extremely expresses on a number of human tumors such as pancreatic, colon, and breast cancer and acts as a functional receptor for Shiga toxin (STx). Then, this toxin can be applied to target Gb3-positive human tumors. In this study, we evaluated DT390-STXB chimeric protein as a new anti-tumor candidate via genetically fusing the DT390 fragment of DT538 (Native diphtheria toxin) to STxB. Methods: This study intended to investigate the DT390- STxB fusion protein structure in silico. Considering the Escherichia coli codon usage, the genomic construct was designed. The properties and the structure of the protein were determined by an in silico technique. The mRNA structure and the physicochemical characteristics, construction, and the stability of the designed chimeric protein were analyzed using computational and bioinformatics tools and servers. Hence, the GOR4 and I-TASSER online web servers were used to predict the secondary and tertiary structures of the designed protein. Result: The results demonstrated that codon adaptation index (CAI) of dt390-stxB chimeric gene raised from 0.6 in the wild type to 0.9 in the chimeric optimized gene. The mfold data revealed that the dt390-stxB mRNA was completely stable to be translated effectively in the novel host. The normal activity of the fusion protein determined by considering the secondary and tertiary structure of each construct. Energy calculation data indicated that the thermodynamic ensemble for mRNA structure was -427.40 kJ/mol. The stability index (SI) of DT390-STxB was 36.95, which is quite appropriate to preserve the stability of the construct. Ultimately, the DT390-STxB was classified as a steady fusion protein according to the Ramachandran plot. Conclusion: Our results showed that DT390-STXB was a stable chimeric protein and it can be recruited as a candidate of novel anti-tumor agents for the development of breast cancer treatment.
