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Genetic and functional interactions between the mitochondrial outer membrane proteins Tom6 and Sam37
Jovana Dukanovic1, Kai S Dimmer, Nathalie Bonnefoy
1Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany.
Molecular and Cellular Biology
|October 3, 2009
Summary
The mitochondrial SAM/TOB complex protein Sam37 interacts with Tom6, crucial for beta-barrel protein biogenesis. This interaction is vital for cell growth at higher temperatures, highlighting Sam37
Area of Science:
- Mitochondrial protein import and biogenesis
- Outer mitochondrial membrane protein insertion
- Protein complex interactions
Background:
- The TOM complex facilitates general mitochondrial protein entry.
- The SAM/TOB complex integrates beta-barrel proteins into the outer mitochondrial membrane.
- Sam37 is a core component of the SAM/TOB complex, essential for growth at elevated temperatures, but its function is unclear.
Purpose of the Study:
- To identify Sam37 interacting partners and elucidate its function.
- To investigate the functional relationship between Sam37 and the TOM complex.
Main Methods:
- Screening for multicopy suppressors of sam37 deletion (sam37Δ).
- Genetic interaction studies between SAM37 and TOM complex components.
- Analysis of cell viability and growth phenotypes under varying temperature conditions.
Main Results:
- Tom6, a small subunit of the TOM complex, was identified as a multicopy suppressor of sam37Δ.
- A tight genetic interaction was observed between Sam37 and Tom6; simultaneous deletion is lethal.
- Overexpression of Sam37 rescues the growth defect of tom6Δ, and Tom6 stabilizes Tom40, a key beta-barrel protein.
Conclusions:
- Sam37 is required for optimal growth at higher temperatures, likely by enhancing the biogenesis of the essential beta-barrel protein Tom40.
- The function of Sam37 in Tom40 biogenesis can be compensated by increased Tom40 stability mediated by Tom6.
- This study reveals a functional link between the SAM/TOB and TOM complexes, crucial for mitochondrial outer membrane protein biogenesis.
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