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Rickettsial permeability. An ADP-ATP transport system.
The Journal of Biological Chemistry
|January 25, 1976
Summary
Rickettsia prowazeki utilizes a specific transport system for ADP and ATP exchange with its host. This carrier-mediated system ensures efficient nucleotide uptake and retention, crucial for parasite survival.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Rickettsia prowazeki is an obligate intracellular bacterium.
- Understanding nutrient transport is vital for Rickettsia biology.
Purpose of the Study:
- To investigate the mechanism of ADP and ATP transport in Rickettsia prowazeki.
- To characterize the specificity and kinetics of the nucleotide transport system.
Main Methods:
- Membrane filtration assays were used to measure nucleotide transport.
- The integrity of Rickettsia was maintained during assays.
- Kinetic parameters and specificity were determined through various experiments.
Main Results:
- A carrier-mediated transport system for ADP and ATP was identified in Rickettsia.
- The system exhibits specific requirements for adenine, ribose, and phosphate moieties.
- Transport kinetics showed saturation, competitive inhibition between ADP and ATP, and a large concentration gradient.
- Efflux was dependent on external nucleotide concentration, and KCN/DNP accelerated transport.
Conclusions:
- Rickettsia prowazeki possesses a highly specific carrier-mediated transport system for adenine nucleotides.
- This system facilitates the exchange of ADP and ATP between the host and parasite.
- Rickettsiae are not generally "leaky" to small molecules, relying on this specific transport mechanism.