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[Inorganic polyphosphates and phosphohydrolases from Halobacterium salinarium]
N A Andreeva1, T V Kulakovskaia, I S Kulaev
1Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Moscow oblast, Russia.
Mikrobiologiia
|September 29, 2000
Summary
Halobacterium salinarium efficiently consumes phosphates, accumulating them during growth. Its pyrophosphatase activity increases over time, with half localized in the cytosol.
Area of Science:
- Microbiology
- Biochemistry
- Cell Biology
Background:
- Halobacterium salinarium is an extremophilic archaeon.
- Phosphate metabolism is crucial for microbial growth and energy storage.
Purpose of the Study:
- To investigate phosphate consumption and polyphosphate accumulation in Halobacterium salinarium.
- To characterize the activity and localization of key phosphatases in this organism.
Main Methods:
- Cultivation of Halobacterium salinarium in liquid medium.
- Measurement of intracellular phosphate and polyphosphate content.
- Assay of pyrophosphatase, polyphosphatase, and nonspecific phosphatase activities.
- Enzyme kinetic analysis and molecular weight determination of pyrophosphatase.
Main Results:
- H. salinarium consumed up to 75% of available phosphates, accumulating significant amounts.
- Acid-soluble oligophosphates peaked during active growth and decreased later.
- Alkali-soluble, acid-insoluble polyphosphates remained relatively constant.
- Phosphatase activities were generally lower than in eubacteria, but pyrophosphatase activity increased throughout cultivation.
- Cytosolic localization and an 86 kDa molecular weight were determined for pyrophosphatase.
Conclusions:
- Halobacterium salinarium exhibits substantial phosphate uptake and storage capabilities.
- The organism's phosphatase enzyme system, particularly pyrophosphatase, shows dynamic regulation during growth.
- Understanding these mechanisms provides insights into extremophile physiology and phosphate management.