Fig. 1

Schematic presentation of the TRAIL protein structure and map of the pNZ8124 secretion vector with expression cassette for controlled hsTRAIL production. a Left—TRAIL is a type II transmembrane protein composed of three major parts: an extracellular TNF-like domain (38–281 aa) with receptor binding region (114–281 aa) and cysteine residue (Cys230), which together with zinc ion are essential for the interaction between three TRAIL-molecules and formation of active TRAIL-homotrimer; a transmembrane domain (18–38 aa) and small cytoplasmic domain (1–18 aa). Transmembrane TRAIL-ligand might be cleaved at an extracellular stalk and released as a soluble molecule. Both forms of TRAIL-ligand (membrane-bound and soluble) are active. Modified from [42]. Right—codon-optimized hsTRAIL-cDNA sequence (coding the region 114–281 aa of human TRAIL) was inserted into pNZ8124 vector plasmid and transformed into L. lactis NZ9000 host strain cells via electroporation. The hsTRAIL expression was based on the Nisin Controlled Gene Expression System (NICE^®) with nisin as the inducer. Protein secretion into the medium was obtained by the presence of sequence for signal peptide of L. lactis usp45 gene (usp45) downstream from promoter region (PnisA). b The pNZ8124 vector contains region for the nisin-inducible promoter (PnisA), an origin of replication sequence (ORI), two genes for the replication proteins (repA, repC), the transcription termination sequence (T) and the gene for the resistance to chloramphenicol (Cm) as the selection marker. The cDNA for hsTRAIL was inserted downstream of the promoter region and the signal sequence for usp45 gene (SP usp45) on the plasmid, between EcoRV and XbaI sites from the multicloning site sequence (MCS). The secretion vector with hsTRAIL-cDNA insert has no any tag sequence added. The vector map is not drawn in scale