Functional mapping of N-terminal residues in the yeast proteome uncovers novel determinants for mitochondrial protein import

by Salom é Nashed, Houssam El Barbry, Médine Benchouaia, Angélie Dijoux-Maréchal, Thierry Delaveau, Nadia Ruiz-Gutierrez, Lucie Gaulier, Déborah Tribouillard-Tanvier, Guillaume Chevreux, Stéphane Le Crom, Benoit Palancade, Frédéric Devaux, Elodie Laine, Mathilde Garcia

N-terminal ends of polypeptides are critical for the selective co-translational recruitment of N-terminal modification enzymes. However, it is unknown whether specific N-terminal signatures differentially regulate protein fate according to their cellular functions. In this work, we developed anin-silico approach to detect functional preferences in cellular N-terminomes, and identified inS.cerevisiae more than 200 Gene Ontology terms with specific N-terminal signatures. In particular, we discovered that Mitochondrial Targeting Sequences (MTS) show a strong and specific over-representation at position 2 of hydrophobic residues known to define potential substrates of the N-terminal acetyltransferase NatC. We validated mitochondrial precursors as co-translational targets of NatC by selective purification of translating ribosomes, and found that their N-terminal signature is conserved inSaccharomycotina yeasts. Finally, systematic mutagenesis of the position 2 in a prototypal yeast mitochondrial protein confirmed its critical role in mitochondrial protein import. Our work highlights the hydrophobicity of MTS N-terminal residues and their targeting by NatC as important features for the definition of the mito...

Source: PLoS Genetics - August 16, 2023 Category: Genetics & Stem Cells Authors: Salom é Nashed Source Type: research