Heterologous transit peptides allow for reporter protein import into chloroplasts with varying efficiency

Abstract

Aim. The stability of recombinant proteins in plants can be improved by targeting into optimal cell compartment. Two transit peptides (TPs), of RuBisCO small subunit from Nicotiana tabacum (tpRbs), and RuBisCO activase from Spinacia oleracea (tpRca), were tested for their ability to insure chloroplast import and increase stability of a reporter GFP. Methods. The sequences encoding TPs were fused with the reporter GFP gene under control of 35S CaMV promoter. The obtained recombinant genes were transiently expressed in Nicotiana excelsior leaves. The level of reporter protein was estimated by surface fluorescence, and GFP subcellular localization was investigated microscopically. Results. Using of both TPs allowed for reporter protein accumulation at higher levels than with control GFP gene without targeting signals. Chloroplast import efficiency was better with tpRca than tpRbs, that resulted in improved reporter stability after tpRca::GFP gene expression. Conclusions. Genetic vectors containing TPs with different efficiency were constructed. They can be used to select the best way for production of valuable proteins in plants.

Key words: plant genetic transformation, subcellular localization, transit peptide.