Identification of Signals Required for Import of the Soybean FAd Subunit of ATP Synthase into Mitochondria

M. Lee, James Whelan

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


The requirements for protein import into mitochondria was investigated by using the targeting signal of theFAd subunit of soybean mitochondrial ATP synthase attached to two different passenger proteins, itsnative passenger and soybean alternative oxidase. Both passenger proteins are soybean mitochondrialproteins. Changing hydrophobic residues at positions )24:25 (Phe:Leu), )18:19 (Ile:Leu) and )12:13(Leu:Ile) of the 31 amino acid cleavable presequence gave more than 50% inhibition of import with bothpassenger proteins. Some other residues in the targeting signal played a more significant role in targeting ofone passenger protein compared to another. Notably changing positive residues (Arg, Lys) had a greaterinhibitory affect on import with the native passenger protein, i.e. greater inhibition of import with FAdmature protein was observed compared to when alternative oxidase was the mature protein. When usingchimeric passenger proteins it was shown that the nature of the mature protein can greatly affect thetargeting properties of the presequence. In vivo investigations of the targeting presequence indicated thatthe presequence of 31 amino acids could not support import of GFP as a passenger protein. However,fusion of the full-length FAd coding sequence to GFP did result in mitochondrial localisation of GFP.Using the latter fusion we confirmed the critical role of hydrophobic residues at positions )24:25 and)18:19. These results support the proposal that core mitochondrial targeting features exist in all presequences,but that additional features exist. These features may not be evident with all passenger proteins.
Original languageEnglish
Pages (from-to)193-203
JournalPlant Molecular Biology
Issue number2
Publication statusPublished - 2004


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