Аннотация
The mitochondrial outer membrane harbors two protein translocases that are essential for cell viability: the translocase of the outer mitochondrial membrane (TOM) and the sorting and assembly machinery (SAM). The precursors of $\beta$-barrel proteins use both translocases-TOM for import to the intermembrane space and SAM for export into the outer membrane. It is unknown if the translocases cooperate and where the $\beta$-barrel of newly imported proteins is formed. We established a position-specific assay for monitoring $\beta$-barrel formation in vivo and in organello and demonstrated that the $\beta$-barrel was formed and membrane inserted while the precursor was bound to SAM. $\beta$-barrel formation was inhibited by SAM mutants and, unexpectedly, by mutants of the central import receptor, Tom22. We show that the cytosolic domain of Tom22 links TOM and SAM into a supercomplex, facilitating precursor transfer on the intermembrane space side. Our study reveals receptor-mediated coupling of import and export translocases as a means of precursor channeling.
- *protein
- cerevisiae
- cerevisiae/*metabolism,to_read
- folding,protein
- membrane
- proteins/chemistry/*metabolism,mutation,porins/chemistry/metabolism,protein
- proteins/chemistry/genetics/*metabolism,saccharomyces
- proteins/genetics/*metabolism,mitochondrial
- secondary,saccharomyces
- structure
- transport
- transport,mitochondria/*metabolism,mitochondrial
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