A model for the catalytic site of F1-ATPase based on analogies to nucleotide-binding domains of known structure

1992 ◽  
Vol 24 (5) ◽  
pp. 453-461 ◽  
Author(s):  
Thomas M. Duncan ◽  
Richard L. Cross
Keyword(s):  
Nucleotide Binding ◽  
Catalytic Site ◽  
F1 Atpase ◽  
Binding Domains

Identification of a Functionally Important Negatively Charged Residue Within the Second Catalytic Site of the SUR1 Nucleotide-Binding Domains

Diabetes ◽  
2004 ◽  
Vol 53 (Supplement 3) ◽  
pp. S123-S127 ◽  
Author(s):  
J. D. Campbell ◽  
P. Proks ◽  
J. D. Lippiat ◽  
M. S.P. Sansom ◽  
F. M. Ashcroft
Keyword(s):  
Nucleotide Binding ◽  
Catalytic Site ◽  
Charged Residue ◽  
Binding Domains

scholarly journals On the Mechanism of MgATP-dependent Gating of CFTR Cl− Channels

2002 ◽  
Vol 121 (1) ◽  
pp. 17-36 ◽  
Author(s):  
Paola Vergani ◽  
Angus C. Nairn ◽  
David C. Gadsby
Keyword(s):  
Molecular Mechanisms ◽  
Structural Data ◽  
Nucleotide Binding ◽  
Catalytic Site ◽  
Nucleotide Analogs ◽  
Binding Domains ◽  
Channel Opening ◽  
Cl Channels ◽  
Excised Patches ◽  
Kinetics Of

CFTR, the product of the gene mutated in cystic fibrosis, is an ATPase that functions as a Cl− channel in which bursts of openings separate relatively long interburst closed times (τib). Channel gating is controlled by phosphorylation and MgATP, but the underlying molecular mechanisms remain controversial. To investigate them, we expressed CFTR channels in Xenopus oocytes and examined, in excised patches, how gating kinetics of phosphorylated channels were affected by changes in [MgATP], by alterations in the chemical structure of the activating nucleotide, and by mutations expected to impair nucleotide hydrolysis and/or diminish nucleotide binding affinity. The rate of opening to a burst (1/τib) was a saturable function of [MgATP], but apparent affinity was reduced by mutations in either of CFTR's nucleotide binding domains (NBDs): K464A in NBD1, and K1250A or D1370N in NBD2. Burst duration of neither wild-type nor mutant channels was much influenced by [MgATP]. Poorly hydrolyzable nucleotide analogs, MgAMPPNP, MgAMPPCP, and MgATPγS, could open CFTR channels, but only to a maximal rate of opening ∼20-fold lower than attained by MgATP acting on the same channels. NBD2 catalytic site mutations K1250A, D1370N, and E1371S were found to prolong open bursts. Corresponding NBD1 mutations did not affect timing of burst termination in normal, hydrolytic conditions. However, when hydrolysis at NBD2 was impaired, the NBD1 mutation K464A shortened the prolonged open bursts. In light of recent biochemical and structural data, the results suggest that: nucleotide binding to both NBDs precedes channel opening; at saturating nucleotide concentrations the rate of opening to a burst is influenced by the structure of the phosphate chain of the activating nucleotide; normal, rapid exit from bursts occurs after hydrolysis of the nucleotide at NBD2, without requiring a further nucleotide binding step; if hydrolysis at NBD2 is prevented, exit from bursts occurs through a slower pathway, the rate of which is modulated by the structure of the NBD1 catalytic site and its bound nucleotide. Based on these and other results, we propose a mechanism linking hydrolytic and gating cycles via ATP-driven dimerization of CFTR's NBDs.

scholarly journals On the location and function of tyrosine beta 331 in the catalytic site of Escherichia coli F1-ATPase.

1992 ◽  
Vol 267 (3) ◽  
pp. 1712-1718 ◽  
Author(s):  
J Weber ◽  
R S Lee ◽  
E Grell ◽  
J G Wise ◽  
A E Senior
Keyword(s):  
Escherichia Coli ◽  
Catalytic Site ◽  
F1 Atpase ◽  
And Function
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