Expression of recombinant TGF β1 protein in tobacco plant and investigation of the effect of Furin protease on processing of the latent form of this protein

TGF β1 is a multifunctional protein that is involved in several biological processes. This protein is initially synthesized as 390 amino acids biologically inactive latent precursor that prior to binding to the TGF β receptors; undergo proteolytic cleavage, to separate mature form of TGF-β1 from its propeptide. The mature form of this protein comprise of the C-terminal 112 amino acids from its precursor. In this study, the potential of two agrobacterium GV3101 and GV3101 (pMP90RK) strains were first investigated for the transformation of Nicotiana benthamiana with pTRAkc-ERH expression vector by creating the pTRAkc/CJG138 (including GFP) as a control construct. The results were analyzed by western blot technique and confocal imaging. Then, in order to transient expression of TGF β1 from its precursor sequence in the tobacco plant, recombinant pTRAkc/ DCF6 and pTRAkc/ DCF7 constructs (containing endoplasmic reticulum retention signal (SEKEDL) and the lacking of this sequence, respectively) were designed and generated. Tobacco plants agro-infiltrated with these constructs alone or in combination with another recombinant construct; harbouring the coding sequence for Furin protease. Results showed that the both of these constructs were successfully expressed in tobacco plants. However, more efficient processing of TGF β1 precursor in infiltrated plants with pTRAkc/ DCF7 construct show that the accumulation of TGF β1 precursor in endoplasmic reticulum prevent to its processing. In addition, in this research was revealed that a Furin-like cleavage between the mature TGF β1 and its propeptide does not occur in N. benthamiana.