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Calcium transport by Frankia sp. strain EAN1pec
1Department of Microbiology, University of New Hampshire, Durham, NH 03824-2617, USA.
Current Microbiology
|June 26, 1998
Summary
Frankia strain EAN1pec exhibits active calcium transport. This nitrogen-fixing bacterium possesses both a calcium uptake system regulated by development and an energy-dependent calcium extrusion mechanism.
Area of Science:
- Microbiology
- Biochemistry
- Plant Science
Background:
- Frankia strain EAN1pec is a nitrogen-fixing symbiont crucial for plant growth.
- Calcium ions play vital roles in cellular processes, including microbial physiology.
- Understanding calcium transport in Frankia is essential for optimizing symbiotic relationships.
Purpose of the Study:
- To investigate the mechanisms of calcium accumulation and extrusion in Frankia strain EAN1pec.
- To determine the role of energy and temperature in calcium transport.
- To identify distinct calcium transport systems within the bacterium.
Main Methods:
- Incubation of Frankia strain EAN1pec cells under different nitrogen sources (N2 vs. NH4Cl) and temperatures (25°C vs. 0°C).
- Assay of calcium accumulation in whole cells and isolated vesicles.
- Utilized respiratory inhibitors and deenergizing conditions to probe energy dependence.
- Investigated calcium efflux from loaded cells.
Main Results:
- N2-grown cells actively accumulated calcium at 25°C, unlike NH4Cl-grown cells.
- Calcium accumulation was energy- and temperature-dependent, inhibited by respiration inhibitors.
- Evidence for an active calcium extrusion mechanism was observed, requiring energy and sensitive to inhibitors.
- Isolated vesicles demonstrated energy-dependent calcium uptake.
Conclusions:
- Frankia strain EAN1pec possesses a developmentally regulated calcium uptake system.
- The bacterium also has an active, energy-dependent calcium extrusion system.
- These two systems collectively regulate calcium homeostasis in Frankia.