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Tom70 enhances mitochondrial preprotein import efficiency by binding to internal targeting sequences.


ABSTRACT: The biogenesis of mitochondria depends on the import of hundreds of preproteins. N-terminal matrix-targeting signals (MTSs) direct preproteins to the surface receptors Tom20, Tom22, and Tom70. In this study, we show that many preproteins contain additional internal MTS-like signals (iMTS-Ls) in their mature region that share the characteristic properties of presequences. These features allow the in silico prediction of iMTS-Ls. Using Atp1 as model substrate, we show that iMTS-Ls mediate the binding to Tom70 and have the potential to target the protein to mitochondria if they are presented at its N terminus. The import of preproteins with high iMTS-L content is significantly impaired in the absence of Tom70, whereas preproteins with low iMTS-L scores are less dependent on Tom70. We propose a stepping stone model according to which the Tom70-mediated interaction with internal binding sites improves the import competence of preproteins and increases the efficiency of their translocation into the mitochondrial matrix.

SUBMITTER: Backes S 

PROVIDER: S-EPMC5881500 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Tom70 enhances mitochondrial preprotein import efficiency by binding to internal targeting sequences.

Backes Sandra S   Hess Steffen S   Boos Felix F   Woellhaf Michael W MW   Gödel Sabrina S   Jung Martin M   Mühlhaus Timo T   Herrmann Johannes M JM  

The Journal of cell biology 20180130 4


The biogenesis of mitochondria depends on the import of hundreds of preproteins. N-terminal matrix-targeting signals (MTSs) direct preproteins to the surface receptors Tom20, Tom22, and Tom70. In this study, we show that many preproteins contain additional internal MTS-like signals (iMTS-Ls) in their mature region that share the characteristic properties of presequences. These features allow the in silico prediction of iMTS-Ls. Using Atp1 as model substrate, we show that iMTS-Ls mediate the bind  ...[more]

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