Yeast mitochondrial biogenesis: a role for the PUF RNA-binding protein Puf3p in mRNA localization.
The asymmetric localization of mRNA plays an important role in coordinating posttranscriptional events in eukaryotic cells. We investigated the peripheral mitochondrial localization of nuclear-encoded mRNAs (MLR) in various conditions in which the mRNA binding protein context and the translation efficiency were altered. We identified Puf3p, a Pumilio family RNA-binding protein, as the first trans-acting factor controlling the MLR phenomenon. This allowed the characterization of two classes of genes whose mRNAs are translated to the vicinity of mitochondria. Class I mRNAs (256 genes) have a Puf3p binding motif in their 3'UTR region and many of them have their MLR properties deeply affected by PUF3 deletion. Conversely, mutations in the Puf3p binding motif alter the mitochondrial localization of BCS1 mRNA. Class II mRNAs (224 genes) have no Puf3p binding site and their asymmetric localization is not affected by the absence of PUF3. In agreement with a co-translational import process, we observed that the presence of puromycin loosens the interactions between most of the MLR-mRNAs and mitochondria. Unexpectedly, cycloheximide, supposed to solidify translational complexes, turned out to destabilize a class of mRNA-mitochondria interactions. Classes I and II mRNAs, which are therefore transported to the mitochondria through different pathways, correlated with different functional modules. Indeed, Class I genes code principally for the assembly factors of respiratory chain complexes and the mitochondrial translation machinery (ribosomes and translation regulators). Class II genes encode proteins of the respiratory chain or proteins involved in metabolic pathways. Thus, MLR, which is intimately linked to translation control, and the activity of mRNA-binding proteins like Puf3p, may provide the conditions for a fine spatiotemporal control of mitochondrial protein import and mitochondrial protein complex assembly. This work therefore provides new openings for the global study of mitochondria biogenesis.
Laboratoire de Génétique Moléculaire CNRS-UMR8541, Ecole Normale Supérieure, Paris, France.
Yann
Y
Saint-Georges
Mathilde
M
Garcia
Thierry
T
Delaveau
Laurent
L
Jourdren
Stephane
S
Le Crom
Sophie
S
Lemoine
Veronique
V
Tanty
Frederic
F
Devaux
Claude
C
Jacq
D001483:Base Sequence; D003513:Cycloheximide / Q000494:pharmacology; D017931:DNA Primers; D017404:In Situ Hybridization, Fluorescence; D008928:Mitochondria / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011691:Puromycin / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology*
D017931:DNA Primers; C510155:PUF3 protein, S cerevisiae; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D011691:Puromycin; D003513:Cycloheximide