Design and construction of a novel multi-epitope chimera linked by the helical linker

The engineered chimeric peptides including functional multi-epitope structures fused by various peptide linkers are widely applied in biotechnological research to improve the expression level and biological activity of chimera. Our study aimed to evaluate the effect of helical linker on solubility, expression level, and folding of multi-epitope chimera containing four epitopes of human T lymphotropic virus type ۱ (HTLV-۱). For this purpose, the chimera sequences connected by the helical linker were inserted into different plasmid vectors and expressed in E. coli strains. The expressed products were analyzed using SDS-PAGE and Western blot techniques. Additionally, the molecular modeling study was performed using iterative threading assembly refinement (I-TASSER) to attain their three-dimensional structures. The low-level of chimera expression was observed for chimera containing the contiguous helical (EAAAK)۵ linker. According to the results of sequence alignment and plasmid stability test, the structure and function of a consecutive helical linker among chimera epitopes were similar to porins as the outer-membrane pore-forming proteins. The molecular modeling results confirmed our experimental study.