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Nucleoside triphosphate pentose ring impact on CFTR gating and hydrolysis
Andrei A Aleksandrov1, Luba Aleksandrov, John R Riordan
1Mayo Foundation and Mayo Clinic Scottsdale, S.C. Johnson Medical Research Center, 13400 E. Shea Blvd., Scottsdale, AZ 85259, USA. aleksand@mayo.edu
FEBS Letters
|May 9, 2002
Summary
Deoxy-ATP (dATP) enhances cystic fibrosis transmembrane conductance regulator (CFTR) channel function more effectively than ATP. Product release or enzyme relaxation is the rate-limiting step in CFTR
Area of Science:
- Biochemistry
- Molecular Biology
- Ion Channel Physiology
Background:
- The pentose ring of adenosine triphosphate (ATP) influences the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein.
- Understanding nucleotide interactions with CFTR is crucial for elucidating its gating mechanisms and potential therapeutic targets.
Purpose of the Study:
- To investigate the effects of deoxy-ATP (dATP) on CFTR channel activity compared to ATP.
- To determine the rate-limiting step in the CFTR hydrolytic cycle involving dATP and ATP.
Main Methods:
- Purification of wild-type CFTR.
- Enzymatic assays to measure CFTR hydrolysis of dATP and ATP.
- Analysis of ion channel kinetics, including opening and closing rates.
Main Results:
- 2'- and 3'-deoxy-ATP (dATP) significantly accelerate CFTR ion channel openings and stabilize the open state compared to ATP.
- Purified wild-type CFTR hydrolyzes dATP.
- The rate constants for dATP and ATP hydrolysis are similar, suggesting product release or enzyme relaxation is rate-limiting.
- dATP interaction bypasses the need for protein kinase A phosphorylation for channel activation.
Conclusions:
- Deoxyribonucleotide binding to CFTR nucleotide-binding domains transmits signals to channel-forming elements more efficiently than ribonucleotides.
- The findings suggest a distinct mechanism for dATP-mediated CFTR activation and highlight the importance of the pentose ring in nucleotide interactions.