Nucleoside triphosphate pentose ring impact on CFTR gating and hydrolysis

• Published in: FEBS letters 2002-05, Vol.518 (1), p.183-188
• Main Authors: Aleksandrov, Andrei A., Aleksandrov, Luba, R. Riordan, John
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - chemistry; Adenosine Triphosphate - metabolism; Adenosine Triphosphate - pharmacology; Animals; ATP hydrolysis; CFTR, cystic fibrosis transmembrane conductance regulator; CHO Cells; Cricetinae; Cystic fibrosis transmembrane conductance regulator; Cystic Fibrosis Transmembrane Conductance Regulator - metabolism; Deoxyadenine Nucleotides - metabolism; Deoxyadenine Nucleotides - pharmacology; Electric Conductivity; Gating kinetics; Hydrolysis; Ion Channel Gating; Kinetics; NBD, nucleotide binding domain; Phosphorylation; PKA, protein kinase A; Ribose - chemistry
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(02)02698-4

Alterations in the pentose ring of ATP have a major impact on cystic fibrosis transmembrane conductance regulator (CFTR) function. Both 2′- and 3′-deoxy-ATP (dATP) accelerate ion channel openings and stabilize open channel structure better than ATP. Purified wild-type CFTR hydrolyzes dATP. The apparent first-order rate constants for hydrolysis at low substrate concentration are the same for dATP and ATP. This suggests that product release and/or relaxation of the enzyme structure to the initial ligand free state is the rate-limiting step in the CFTR hydrolytic cycle. Circumvention of the normal requirement for protein kinase A phosphorylation of the R-domain for channel activation implies that the impact of the deoxyribonucleotide interaction with the nucleotide binding domains is transmitted to the channel-forming elements of the protein more readily than that of the ribonucleotide.