Increasing foreign protein yields in the plant secretory pathway by overexpression of plant transmembrane bZIP transcription factors

MAZZINI, FLAVIA NOELIA; PETRUCCELLI, SILVANA

Foz Iguazu

Congreso; International Plant Molecular Biology Congress (IPMB); 2015

International Society for Plant Molecular Biology (ISPMB)

Plants are well known for their high capacity of synthesis of proteins and other polymers. This capacity is unique and its knowledge will be important for the development of plant-based platforms for the production of proteins of interest. There are a few examples of ?professional secretory cells?, such as mammalian plasmatic cells and cells of developing seeds but the signals that trigger its differentiation are barely known. There are several transcription factors that are produced in developing seeds during a time period when storage proteins are synthesized, which might be involved in this differentiation process. Based on maturing Arabidopsis seeds transcriptomic, several transcription factors with bZIP domains, similar to XBP1 (X-box binding protein 1) were chosen as candidates to be involved in secretory cell differentiation. In this work, we studied the effect of the full length bZIP17 and bZIP60 and a deletion version of bZIP60 lacking the C-terminal (bZIP60dtc) on the expression of reporter proteins: beta glucuronidase (GUS) sorted to the endoplasmic reticulum (ER-GUS-) and also a cytoplasmic version (cyto-GUS) and also fluorescent proteins (FP) markers of different compartments of the secretory pathway.. Agrobacterium tumefaciens carrying the effectors and reporters constructs were infiltrated in N. benthamiana leaves and GUS activity, and amount of FP were analyzed 4 days post--infiltration. An increment of ER-GUS activity was observed in presence of the different bZIPs in comparison of the GUS activity level without effectors. Contrary to effect observed in the secretory pathway cytosolic GUS activity was lower in the present of the effectors bZIP than in its absent.Increase in ER-FP accumulation was detected by immunoblot. In conclusion, the effector bZIPs increase protein yields along the secretory pathway but not in the cytoplasm