ATP-dependent fructose uptake system in Deinococcus radiodurans.
Hui-Yu Lee1, Minoti Magotra, Tit-Yee Wong
1Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan, Republic of China.
Applied Microbiology and Biotechnology
|August 9, 2011
Summary
Deinococcus radiodurans metabolizes fructose using ATP, not PEP, despite lacking a functional fructose-specific cytosolic component. This suggests an alternative fructose phosphorylation pathway in this bacterium.
Area of Science:
- Microbiology
- Biochemistry
- Bacterial Physiology
Background:
- The bacterial phosphoenolpyruvate (PEP)-dependent group translocation system (PTS) is crucial for sugar phosphorylation and translocation.
- Deinococcus radiodurans possesses the membrane-bound component (FruA) for fructose PTS but has a pseudogene for the cytosolic component (FruB).
- Despite the defective FruB, D. radiodurans readily metabolizes fructose, indicating an alternative pathway.
Purpose of the Study:
- To investigate the mechanism of fructose phosphorylation in Deinococcus radiodurans.
- To elucidate the role of ATP versus PEP as the phosphate donor in fructose phosphorylation.
- To compare the fructose metabolism pathway in D. radiodurans with the canonical PTS.
Main Methods:
- In vitro phosphorylation assays using cell membranes and cytoplasmic fractions of D. radiodurans.
- Investigating the effect of ATP, PEP, sodium fluoride, and specific antiserum on fructose phosphorylation.
- Complementation assays using membrane and cytoplasmic fractions from D. radiodurans and Rhodobacter capsulatus.
Main Results:
- Fructose phosphorylation in D. radiodurans requires both cell membranes and cytoplasmic fractions.
- Fructose phosphorylation utilizes ATP, not PEP, as the phosphate donor and is sensitive to kinase inhibitors.
- Complementation assays revealed an ATP-dependent phosphorylation with D. radiodurans membranes and R. capsulatus cytosol, and PEP-dependent phosphorylation with R. capsulatus membranes and D. radiodurans cytosol.
Conclusions:
- Deinococcus radiodurans employs an alternative, non-PEP-dependent pathway for fructose phosphorylation, likely involving ATP.
- The functional FruA protein in D. radiodurans can interact with components from other bacteria to mediate PEP-dependent phosphorylation.
- This study highlights the metabolic flexibility and unique biochemical pathways present in extremophilic bacteria like D. radiodurans.
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