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Dual targeting and function of a protease in mitochondria and chloroplasts
Author(s) -
Bhushan Shashi,
Lefebvre Benoit,
Ståhl Annelie,
Wright Sarah J,
Bruce Barry D,
Boutry Marc,
Glaser Elzbieta
Publication year - 2003
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400011
Subject(s) - chloroplast , green fluorescent protein , mitochondrion , biochemistry , biology , mutant , methionine , protease , fusion protein , peptide , amino acid , microbiology and biotechnology , recombinant dna , enzyme , gene
Here we show, using the green fluorescent protein (GFP) fusion system, that an Arabidopsis thaliana zinc‐metalloprotease ( At Zn‐MP) is targeted to both mitochondria and chloroplasts. A deletion mutant lacking the amino‐terminal 28 residues, with translation initiation at the second methionine residue, was imported into chloroplasts only. However, a mutated form of the full‐length targeting peptide, in which the second methionine residue is changed to leucine, was imported to both organelles. No GFP fluorescence was detected when a frame‐shift mutation was introduced between the first and second ATG codons of the Zn‐MP–GFP construct, suggesting no alternative translational initiation. Our results show that the dual targeting of the Zn‐MP is due to an ambiguous targeting peptide. Furthermore, we show that the recombinant At Zn‐MP degrades mitochondrial and chloroplastic targeting peptides, indicating its function as a signal peptide degrading protease in both mitochondria and chloroplasts.