Recombinant Saccharomyces cerevisiae Mitochondrial import inner membrane translocase subunit TIM54 (TIM54)
Description
Introduction to Recombinant Saccharomyces cerevisiae Mitochondrial Import Inner Membrane Translocase Subunit TIM54 (TIM54)
Recombinant Saccharomyces cerevisiae Mitochondrial import inner membrane translocase subunit TIM54 (TIM54) is a crucial protein involved in the mitochondrial import process, specifically in the insertion of polytopic proteins into the mitochondrial inner membrane. TIM54 is part of the TIM22 complex, which plays a pivotal role in maintaining mitochondrial function by ensuring the proper integration of proteins necessary for energy production and other cellular processes.
Structure and Function of TIM54
TIM54 is an integral membrane protein located in the mitochondrial inner membrane. It contains potential membrane-spanning segments, which are essential for its function in protein insertion . The protein is involved in two main functions: it acts as a scaffolding component for the TIM22 complex, ensuring its stability, and it facilitates the assembly of the Yme1p protease complex, which is crucial for protein turnover within mitochondria .
Key Functions of TIM54:
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Stability and Assembly of TIM22 Complex: TIM54 works alongside Tim22p to form a distinct import complex separate from the Tim23p-Tim17p complex, which is responsible for translocating proteins across the inner membrane .
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Assembly of Yme1p Complex: TIM54 is essential for assembling Yme1p into a proteolytically active complex, which is imported via the TIM23 pathway .
Role in Mitochondrial Protein Import
The mitochondrial inner membrane contains two primary import complexes: the Tim23p-Tim17p complex for translocating matrix-targeted proteins and the Tim54p-Tim22p complex for inserting polytopic proteins into the inner membrane . TIM54 is critical for the latter process, ensuring that proteins with multiple membrane-spanning segments are correctly inserted into the inner membrane.
Comparison of Import Complexes:
| Complex | Function | Key Components |
|---|---|---|
| Tim23p-Tim17p | Translocation of matrix-targeted proteins across the inner membrane | Tim23p, Tim17p |
| Tim54p-Tim22p | Insertion of polytopic proteins into the inner membrane | Tim54p, Tim22p, Tim18p |
Research Findings and Implications
Studies have shown that mutations in TIM54 can lead to defects in protein import and assembly, resulting in mitochondrial dysfunction. For instance, the tim54-1 mutation destabilizes Tim22p and impairs the import of certain inner membrane proteins . Additionally, TIM54's role in assembling the Yme1p complex highlights its importance in protein turnover and maintaining mitochondrial health .
Impact of TIM54 Mutations:
Product Specs
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Target Background
- Tim54p links protein import, assembly, and turnover pathways within the mitochondrion. PMID: 17893242
KEGG: sce:YJL054W
STRING: 4932.YJL054W
Q&A
FAQ: Recombinant Saccharomyces cerevisiae Mitochondrial Inner Membrane Translocase Subunit TIM54 (TIM54)
Advanced Research Questions
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How does Tim54 interact with the Tim22 complex during protein insertion?
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Genetic suppression: Overexpression of TIM22 (but not TIM23 or TIM17) rescues tim54-1 growth defects .
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Co-immunoprecipitation: Tim54p and Tim22p form a stable complex distinct from Tim23p–Tim17p .
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Destabilization analysis: tim54-1 mutation reduces Tim22p stability, indicating functional interdependence .
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What experimental approaches resolve contradictions in Tim54’s import pathway?
Conflicting data exist on whether Tim54 uses Tom70 (carrier route) or Tom20 (N-terminal signal route) . Key methodologies:-
Receptor-specific antibodies: Blocking Tom70 reduces Tim54 import by ~60%, while Tom20 inhibition has minor effects .
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mtHsp70 dependency: ssc1–3 mutants (defective mtHsp70) show partial Tim54 import inhibition, unlike strict matrix precursors .
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Comparative analysis:
Import Feature Tim54 Tim22 Matrix Proteins Tom70 dependence Moderate High Low mtHsp70 requirement Partial None Full Δψ dependence Yes Yes Yes -
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How is Tim54’s role in IM insertion distinct from Tim23-mediated translocation?
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Functional separation:
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Import assays:
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Methodological Challenges
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How to validate Tim54’s essentiality in non-Saccharomyces systems?
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What techniques identify Tim54-associated proteins in native membranes?
