Simultaneous targeting of pea glutathione reductase and of a bacterial fusion protein to chloroplasts and mitochondria in transgenic tobacco

Abstract

Summary N-terminal presequencas from cDNAs encoding mitochondrion-or chloroplast-specific proteins are able, with variable efficiencies, to target preprotsins to their respective organelles, in the few cases studied in which a nuclearencoded protein is found in both these orgeneiles, each compartment-specific isoform is encoded by a separate gene. Glutathione reductase (GR) from peas is encoded by a single nuclear gene and yet GR is distributed between chloroplasts, mitochondda and the cytosoL Previous sequence analysis of a full-length GR cDNA revealed the presence of a putative plastid transit peptide. However, expression of this cDNA in transgenic tobacco resulted in substantially elevated GR activities in beth chloroplasts and mitochondria in four independent lines examined. There was no effect on expression of the endogenous tobacco GR genes. Replacement of the GR presequenca with presequencas from pea rbcS (chloroplast) and Nicotiana plumbaginifolia Mn-SOD (mitochonddon) resulted in targeting of GR only into the appropriate organeile. Expression of a fusion protein between the amino terminal region of GR and phosphinothricin acatyl transferase resulted in targeting of the foreign proteinto chloroplasts and mitochondria. Thus, the pea GR presequence is capable of co-targeting this enzyme or a foreign protein to chloroplasts and miti:¢hondria in vivo. This is the first example of co-targeting by a higher plant preprotein.

The Mitochondrial Type II Peroxiredoxin F Is Essential for Redox Homeostasis and Root Growth of Arabidopsis thaliana under Stress

“…Chew et al (25) demonstrated dual targeting of ascorbate peroxidase (At4g08390), monodehydroascorbate reductase (At1g63940), and glutathione reductase (At3g54660) to both the plastid and mitochondrion, whereas a specific dehydroascorbate reductase (At3g54660) was solely imported into the mitochondria. The work extended previous investigations that suggested dual targeting of glutathione reductase (26) and solved the contradiction between reported activities of the respective enzyme activities in mitochondrial preparations and the lack of corresponding genes with unequivocal information for mitochondrial targeting in the Arabidopsis thaliana genome (27). Recently, PrxII F was identified as mitochondrial type II peroxiredoxin.…”

Widespread dual targeting of proteins in land plants: When, where, how and why

“…The first dual targeted protein identified in plants was the Pisum sativum (pea) glutathione reductase (GR) which was shown to be targeted to both mitochondria and chloroplasts. 1 Since then the number of proteins shown to be dual targeted in plants is more than 250 ( Table 1). Dual targeting can refer to a protein targeted to any two locations, such as mitochondria and chloroplasts, mitochondria and the nucleus, 2 mitochondria and peroxisomes, 3 mitochondria and cytoplasm, 4 mitochondria and endoplasmic reticulum, 5 mitochondria and golgi, 6 mitochondria and plasma…”

Cloning and characterization of a cDNA encoding a bacteriophage-type RNA polymerase from the higher plant Chenopodium album

“…On the other hand, the possibility exists that the same RNA polymerase (encoded by one nuclear gene) is targeted to both organelles. Thus, it has been demonstrated that the presequence of pea gluthathione reductase is capable of co-targeting this enzyme or a foreign protein simultaneously to chloroplasts and mitochondria in vivo (33). However, analysis of the C.album sequence by a knowledge-based system for prediction of protein targeting, PSORT (http://psort.nibb.ac.jp), does not reveal any features of the N-terminus consistent with targeting to plastids.…”