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Evidence for a link between translocation and processing during protein import into soybean mitochondria
J Whelan1, M R Tanudji, M K Smith
1Department of Biochemistry, University of Western Australia, Nedlands, Perth, Australia.
Biochimica Et Biophysica Acta
|June 5, 1996
Summary
Metal chelators that cross soybean mitochondrial membranes inhibit protein import and processing. This suggests metal-dependent steps are crucial for protein translocation and processing within mitochondria.
Area of Science:
- Plant Biology
- Mitochondrial Biology
- Molecular Biology
Background:
- Protein import into mitochondria is essential for cellular function.
- Mitochondrial protein import and processing are complex processes.
- The role of metal ions in these processes is not fully understood.
Purpose of the Study:
- To investigate the effect of metal chelators on protein import into soybean mitochondria.
- To determine if metal-dependent steps are involved in protein translocation and processing.
Main Methods:
- Using isolated soybean mitochondria and precursor proteins.
- Employing metal chelators with varying membrane permeability (1,10-phenanthroline, EDTA, 1,7-phenanthroline, 4,7-phenanthroline).
- Utilizing a mutagenesis approach to inhibit a known metal-dependent processing step.
Main Results:
- 1,10-phenanthroline, a membrane-permeable chelator, abolished import of alternative oxidase and ATP synthase F(1)d subunit.
- Non-permeable chelators (EDTA, 1,7-phenanthroline, 4,7-phenanthroline) had no effect on import.
- Inhibiting a metal-dependent processing step via mutagenesis also inhibited protein import.
Conclusions:
- Protein translocation across mitochondrial membranes in soybean is dependent on metal ions.
- Mitochondrial protein processing is also a metal-dependent step.
- Translocation and processing may be directly linked through metal-dependent mechanisms in soybean mitochondria.