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Na+/adenosine co-transport in Vibrio parahaemolyticus
Abstract:
Adenosine transport in Vibrio parahaemolyticus was studied. Na+ greatly stimulated adenosine uptake. Addition of adenosine to a cell suspension under anaerobic conditions elicited Na+ uptake, and the Na+ uptake was inhibited by monensin, an Na+ ionophore. Imposition of an electrochemical potential of Na+ or a membrane potential in energy-depleted cells elicited adenosine uptake. Therefore, adenosine transport in this organism was concluded to proceed by an Na+/adenosine co-transport mechanism. The Na+/adenosine co-transport system was induced when cells were grown in the presence of adenosine, and repressed by glucose. Although Na+ uptake elicited by adenosine was reduced by glucose, it was enhanced by methyl alpha-glucoside, which reduced the intracellular ATP level. Thus, the effects of glucose and the glucoside on the Na+/adenosine co-transport system did not seem to be due to inducer exclusion, but to be related to the intracellular ATP level.
Insights
Vibrio parahaemolyticus transports adenosine using a sodium/adenosine co-transport mechanism. This process is regulated by intracellular ATP levels and influenced by specific sugars.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Adenosine is a crucial nucleoside involved in various cellular processes.
- Understanding nucleoside transport mechanisms is vital for comprehending bacterial physiology and metabolism.
Purpose of the Study:
- To elucidate the mechanism of adenosine transport in the marine bacterium Vibrio parahaemolyticus.
- To investigate the role of sodium ions and electrochemical gradients in adenosine uptake.
- To determine the regulatory factors affecting the Na+/adenosine co-transport system.
Main Methods:
- Studying adenosine uptake in Vibrio parahaemolyticus under various conditions.
- Measuring sodium ion (Na+) uptake in response to adenosine.
- Utilizing ionophores (monensin) and manipulating membrane potential.
- Investigating the effects of different carbon sources (glucose, methyl alpha-glucoside) on transport and Na+ uptake.
Main Results:
- Sodium ions (Na+) significantly stimulate adenosine uptake in Vibrio parahaemolyticus.
- Adenosine addition elicits Na+ uptake, inhibited by monensin, indicating a coupled transport.
- Imposing Na+ electrochemical potential or membrane potential drives adenosine uptake.
- The Na+/adenosine co-transport system is induced by adenosine and repressed by glucose.
- Glucose and methyl alpha-glucoside affect transport via intracellular ATP levels, not inducer exclusion.
Conclusions:
- Adenosine transport in Vibrio parahaemolyticus occurs via an Na+/adenosine co-transport mechanism.
- Intracellular ATP levels play a key role in regulating the Na+/adenosine co-transport system.
- The findings provide insights into the bioenergetics and regulation of nucleoside transport in bacteria.