The access of metabolites into yeast mitochondria in the presence and absence of the voltage dependent anion selective channel (YVDAC1)

• Authors: Hanna Kmita , Olgierd Stobienia , Jan Michejda
• Languages of publication: EN

Abstracts

EN

Since yeast Saccharomyces cerevisiae mutants depleted of the voltage dependent anion selective channel (YVDAC1) are still able to grow on a non-fermentable carbon source, a functional transport system in the outer mitochondrial membrane must exist to support the access of metabolites into mitochondria. It was assumed that the properties of the system could be inferred from the differences in the results observed between wild type and mutant mitochondria since no crucial differences in this respect between the two types of mitoplasts were observed. YVDAC1-depleted mitochondria displayed a highly reduced permeability of the outer membrane, which was reflected in increased values of K^{NADH}_{0.5} for respiration and K^{ADP}_{0.5} for triggering phosphorylating state as well as in delayed action of carboxyatractylate (CATR) in inhibition of phosphorylating state. The parameters were chosen to express the accessibility of the applied species to the intermembrane space. The passage of the molecules through the outer membrane depleted of YVDAC1 could be partially improved in the presence of bivalent cations (Mg^{2+}, Ca^{2+}), as in their presence lower values of the calculated parameters were obtained. The restrictions imposed on the transport of molecules through the YVDAC1-depleted outer membrane resulted in a competition between them for the access to the intermembrane space as measured by changes in parameters observed for a given species in the presence of another one. The competition was stronger in the absence of Mg^{2+} and depended on charge and size of transported molecules, as the strongest competitor was CATR and the weakest one - {NADH}. Thus, it can be concluded that the transport system functioning in the absence of YVDAC1 is modulated by bivalent cations and charge as well as size of transported molecules. Since an increased level of respiration due to the dissipation of Δψ causes an increase of K^{NADH}_{0.5} in both wild type and YVDAC1-depleted mitochondria it is concluded that a common property of YVDAC1 and the system functioning in YVDAC1-depleted mitochondria seems to be the dependence of the capacity on the level of mitochondrial respiration.

Keywords

EN

metabolite transport; yeast voltage-dependent anion selective channel (YVDAC1); YVDAC1-depleted mutants; mitochondria

• Publisher: Polish Biochemical Society
• Journal: Acta Biochimica Polonica
• Year: 1999
• Volume: 46
• Issue: 4
• Pages: 991-1000

Dates

published

1999

received

1999-06-26

revised

1999-10-01

accepted

1999-11-09

Contributors

author

Hanna Kmita

• Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań University, A. Fredry 10, 61-701 Poznań, Poland

author

Olgierd Stobienia

• Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań University, A. Fredry 10, 61-701 Poznań, Poland

author

Jan Michejda

• Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań University, A. Fredry 10, 61-701 Poznań, Poland