Chloroplast targeting of bacterial β-glucuronidase with a pea transit peptide in transgenic tobacco plants

Abstract

Transit peptides located at the amino termini of the chloroplast precursor proteins are necessary and sufficient components to accomplish import of chloroplast proteins in切 chloroplasts. We introduced a chimeric gene consisting of a coding sequence of Pisum sativum small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase (rbcS) transit peptide and the gene coding for bacterial p-glucuronidase (GUS) into tobacco (Nicotiana taba-cum L.) cells by Agrobacterium tumefaciens/binstry vector system. Transformed tobacco cells with the chimeric gene were in vitro regenerated and the transgenic plants developed were assayed for the expression of GUS and targeting of GUS into chloroplasts by northern blot analysis and measurement of GUS activity. Northern blot analysis confirmed that the fused gene of Gus and the coding sequence for the transit peptide was properly integrated into tobacco chromosome and transcribed. Fractionated chloroplasts from the transgenic tobacco plants showed significant levels of GUS activities. These results indicate that the pea transit peptide is sufficient to transport GUS across the chloroplast envelope into chloroplast in transgenic tobacco plants.