Age-related changes in proline mitochondrial transport and metabolism in Jerusalem artichoke tubers

Mitochondrial aging has received considerable attention in biomedicine, but little is known about the regulatory mechanisms responsible for the aging in plant mitochondria. Considering the variety of roles played by proline in stress physiology, aging effects on proline concentrations as well as proline mitochondrial transport were studied in tubers of Jerusalem artichoke. We demonstrate, that, there are two distinct carriers for proline transport in mitochondria isolated from aged-dehydrated slices tubers, namely a carrier solely for proline and a proline/glutamate antiporter. We found that externally added proline generates a mitochondrial membrane potential with a rate depending on the transport of proline across the mitochondrial inner membrane. The dependence of the rate of generation of ΔΨ on increasing proline concentrations exhibits hyperbolic kinetics. Proline transport is inhibited by the non-penetrant thiol reagent mersalyl. The dependence of the rate of glutamate efflux on increasing proline concentration shows saturation kinetics. Conversely, in mitochondria isolated from fresh slices tubers externally added proline failed to generate a mitochondrial membrane potential. Mitochondrial aging has received considerable attention in biomedicine, but little is known about the regulatory mechanisms responsible for the aging in plant mitochondria. Considering the variety of roles played by proline in stress physiology, aging effects on proline concentrations as well as proline mitochondrial transport were studied in tubers of Jerusalem artichoke. We demonstrate, that, there are two distinct carriers for proline transport in mitochondria isolated from aged-dehydrated slices tubers, namely a carrier solely for proline and a proline/glutamate antiporter. We found that externally added proline generates a mitochondrial membrane potential with a rate depending on the transport of proline across the mitochondrial inner membrane. The dependence of the rate of generation of ΔΨ on increasing proline concentrations exhibits hyperbolic kinetics. Proline transport is inhibited by the non-penetrant thiol reagent mersalyl. The dependence of the rate of glutamate efflux on increasing proline concentration shows saturation kinetics. Conversely, in mitochondria isolated from fresh slices tubers externally added proline failed to generate a mitochondrial membrane potential.