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Assaying for Inorganic Polyphosphate in Bacteria
Published on: January 21, 2019
Different chain length specificity among three polyphosphate quantification methods
Ryo Ohtomo1, Yoko Sekiguchi, Tomoko Kojima
1National Agricultural Research Organization, National Institute of Livestock and Grassland Science, Nasushiobara, Tochigi 329-2793, Japan. rotm@affrc.go.jp
Analytical Biochemistry
|August 30, 2008
Summary
Polyphosphate assays using polyphosphate kinase (PPK) may underestimate short-chain polyphosphates in arbuscular mycorrhizal fungi. Yeast exopolyphosphatase (PPX) assays are more sensitive to shorter polyphosphate chains, offering a better detection method.
Area of Science:
- Biochemistry
- Mycology
- Plant Science
Background:
- Polyphosphates are vital molecules in all living organisms, playing diverse biochemical roles.
- Arbuscular mycorrhizal fungi are known to store polyphosphates, crucial for their symbiotic functions.
- Existing polyphosphate detection methods may not accurately reflect the full polyphosphate profile in certain biological samples.
Purpose of the Study:
- To evaluate the effectiveness of different enzymatic assays for polyphosphate detection in arbuscular mycorrhizal fungi.
- To determine the sensitivity of polyphosphate kinase (PPK) and exopolyphosphatase (PPX) assays to varying polyphosphate chain lengths.
- To identify the most suitable method for quantifying short-chain polyphosphates in mycorrhizal roots.
Main Methods:
- Comparison of polyphosphate quantification using polyphosphate kinase (PPK) reverse reaction coupled with luciferase assay versus yeast exopolyphosphatase (PPX) assay.
- Utilized polyphosphate chain length standards to analyze the substrate specificity of both enzymatic assays.
- Assessed the efficiency of each method in detecting polyphosphates of different chain lengths.
Main Results:
- The PPK assay failed to detect significant polyphosphate accumulation in some mycorrhizal root samples.
- Applying the PPX assay revealed substantially higher polyphosphate levels compared to the PPK assay in the same samples.
- The PPX method demonstrated high efficiency in detecting short-chain polyphosphates (average chain length quantifiable >50% efficiency = 3), while the PPK method was more effective for longer chains (average chain length = 38).
Conclusions:
- The PPX assay is more appropriate for detecting short-chain polyphosphates in arbuscular mycorrhizal fungi than the PPK assay.
- The ratio of PPK to PPX values can serve as a simple index for assessing polyphosphate chain length distribution.
- Accurate polyphosphate measurement in mycorrhizal symbiosis requires careful consideration of assay methodology and polyphosphate chain length.
