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An interplay between the TOM complex and porin isoforms in the yeast Saccharomyces cerevisiae mitochondria
N Antos1, M Budzińska, H Kmita
1Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Adam Mickiewicz University, Fredry 10, 61-701 Poznan, Poland.
Abstract:
The outer mitochondrial membrane of Saccharomyces cerevisiae contains two isoforms of mitochondrial porin, known also as the voltage-dependent anion channel. The isoform termed here porin1 displays channel-forming activity enabling metabolite transport whereas the second one, termed here porin2, does not form a channel and its function is still not clear. We have shown recently that in the absence of porin1, the channel within the protein import machinery (the TOM complex) is essential for metabolite transport across the outer membrane [Kmita and Budzińska, Biochim. Biophys. Acta 1509 (2000) 6044-6050]. Here, we report that the TOM complex channel may also serve as a supplementary pathway for metabolites in the presence of porin1 when the permeability of the latter is limited and the role of the TOM complex seems to increase when porin2 is depleted.
Insights
The TOM complex channel aids metabolite transport across the outer mitochondrial membrane in Saccharomyces cerevisiae, especially when porin1 is limited or porin2 is depleted.
Area of Science:
- Mitochondrial biology
- Cellular transport mechanisms
- Biochemistry
Background:
- Saccharomyces cerevisiae outer mitochondrial membrane has two porin isoforms: porin1 (channel-forming, metabolite transport) and porin2 (non-channel-forming, unclear function).
- Previously, the TOM complex channel was essential for metabolite transport when porin1 was absent.
Purpose of the Study:
- To investigate the role of the TOM complex channel in metabolite transport.
- To understand its function in conjunction with porin1 and porin2.
Main Methods:
- Analysis of metabolite transport across the outer mitochondrial membrane.
- Investigating the roles of porin1, porin2, and the TOM complex.
Main Results:
- The TOM complex channel serves as a supplementary pathway for metabolite transport.
- This supplementary role is evident when porin1 permeability is reduced.
- The TOM complex's role increases upon depletion of porin2.
Conclusions:
- The TOM complex channel provides an alternative route for metabolite transport.
- Its contribution is significant under conditions of altered porin activity or presence.