A novel intermembrane space–targeting signal docks cysteines onto Mia40 during mitochondrial oxidative folding

A nine-residue intermembrane-targeting signal brings the active Cys of substrate proteins into contact with Mia40 oxidase for folding and import into mitochondria

Analyse didactique d'un dispositif visant à reconnaître les stéréotypes de sexe d'élèves de CP dans une perspective de changement

Analyse d'une séquence sur l'égalité entre les filles et les garçons co-élaborée avec une enseignante de CP (recherche collaborative) dans le but de faire changer les représentations des élèves sur les stéréotypes de sexe. La séquence s'appuie sur le repérage de stéréotypes de sexe dans des albums de littérature de jeunesse. Les séances sont filmées et une discussion menée en amont, pendant et après la séquence avec l'enseignante. Une séance débattant de différents stéréotypes est retenue et analysée d'un point de vue didactique. Il résulte de cette étude que surtout les meilleurs élèves profitent réellement de la séquence pour faire évoluer leurs représentations, malgré toute la volonté de changement de l'enseignante

Role of Twin Cys-Xaa9-Cys Motif Cysteines in Mitochondrial Import of the Cytochrome c Oxidase Biogenesis Factor Cmc1

The Mia40 import pathway facilitates the import and oxidative folding of cysteine-rich protein substrates into the mitochondrial intermembrane space. Here we describe the in vitro and in organello oxidative folding of Cmc1, a twin CX(9)C-containing substrate, which contains an unpaired cysteine. In vitro, Cmc1 can be oxidized by the import receptor Mia40 alone when in excess or at a lower rate by only the sulfhydryl oxidase Erv1. However, physiological and efficient Cmc1 oxidation requires Erv1 and Mia40. Cmc1 forms a stable intermediate with Mia40 and is released from this interaction in the presence of Erv1. The three proteins are shown to form a ternary complex in mitochondria. Our results suggest that this mechanism facilitates efficient formation of multiple disulfides and prevents the formation of non-native disulfide bonds

Mitochondrial Biogenesis, Switching the Sorting Pathway of the Intermembrane Space Receptor Mia40*S⃞

Mitochondrial precursor proteins are directed into the intermembrane space via two different routes, the presequence pathway and the redox-dependent MIA pathway. The pathways were assumed to be independent and transport different proteins. We report that the intermembrane space receptor Mia40 can switch between both pathways. In fungi, Mia40 is synthesized as large protein with an N-terminal presequence, whereas in metazoans and plants, Mia40 consists only of the conserved C-terminal domain. Human MIA40 and the C-terminal domain of yeast Mia40 (termed Mia40core) rescued the viability of Mia40-deficient yeast independently of the presence of a presequence. Purified Mia40core was imported into mitochondria via the MIA pathway. With cells expressing both full-length Mia40 and Mia40core, we demonstrate that yeast Mia40 contains dual targeting information, directing the large precursor onto the presequence pathway and the smaller Mia40core onto the MIA pathway, raising interesting implications for the evolution of mitochondrial protein sorting