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Free and bound magnesium in fungi and yeasts
Abstract:
The content of total, bound and osmotically free magnesium was estimated in various fungi and in the yeast Saccharomyces cerevisiae. Total magnesium increases at lower growth rates of Endomyces magnusii and Penicillium chrysogenum 140A as well as during the logarithmic stage of growth of Penicillium chrysogenum Q-176. The binding of magnesium requires orthophosphate, decreasing during lack of external phosphate when the intracellular concentration of free magnesium rises. The fungi were found to contain a novel form of bound magnesium, a polymeric magnesium orthophosphate (PO Mg), which appears to take part in the control of free magnesium level in Penicillium chrysogenum Q-176. The level of free magnesium is proportional to the growth rate of Endomyces magnusii and Penicillium chrysogenum Q-176 and 140A. Total, as well as free, magnesium changes less than three-fold as external Mg concentration is changed 13,000-fold. The magnesium is taken up against concentration gradients of 1 : 25 to 1 : 1300, the metal being distributed non-uniformly in the cells of Saccharomyces cerevisiae.
Insights
Magnesium levels in fungi, including yeast, are influenced by growth rate and phosphate availability. A novel polymeric magnesium orthophosphate (PO Mg) may regulate free magnesium, which is proportional to growth rate.
Area of Science:
- Biochemistry
- Mycology
- Cell Biology
Background:
- Magnesium is an essential element for fungal growth and cellular processes.
- Understanding magnesium homeostasis is crucial for fungal physiology.
Purpose of the Study:
- To investigate the content and distribution of total, bound, and free magnesium in various fungi and Saccharomyces cerevisiae.
- To explore the relationship between magnesium levels, growth rate, and phosphate availability.
Main Methods:
- Estimation of total, bound, and osmotically free magnesium in fungal species.
- Analysis of magnesium content in relation to growth rate and external phosphate concentrations.
Main Results:
- Total magnesium increased with lower growth rates in Endomyces magnusii and Penicillium chrysogenum.
- Magnesium binding is dependent on orthophosphate; its decrease leads to increased intracellular free magnesium.
- A novel polymeric magnesium orthophosphate (PO Mg) was identified in Penicillium chrysogenum, potentially regulating free magnesium.
- Free magnesium levels correlated with growth rates across studied fungi.
- Fungal cells actively uptake magnesium against significant concentration gradients.
Conclusions:
- Fungal magnesium homeostasis is a complex process influenced by growth rate, phosphate, and a novel bound magnesium form.
- The identified polymeric magnesium orthophosphate plays a role in controlling intracellular free magnesium levels.
- Fungi maintain magnesium levels within a narrow range despite wide external concentration fluctuations.