The Origin Recognition Complex (ORC) is a six-protein assembly that specifies the sites of DNA replication initiation in S. cerevisiae. Origin recognition by ORC requires ATP. Here, we demonstrate that two subunits, Orc1p and Orc5p, bind ATP and that Orc1p also hydrolyzes ATP. ATP binding and hydrolysis by Orc1p are both regulated by origin DNA in a sequence-specific manner. ATP binding to Orc1...

The periplasmic histidine transport system (permease) of Escherichia coli and Salmonella typhimurium is composed of a soluble, histidine-binding receptor located in the periplasm and a complex of three membrane-bound proteins of which one, HisP, was shown previously to bind ATP. These permeases are energized by ATP. HisP is a member of a family of membrane transport proteins which is conserved ...

Substrate and product concentrations are shown to have a pronounced effect on the pattern of the isotopic exchange reactions which accompany succinate-driven oxidative phosphorylation by beef heart submitochondrial particles. Rapid removal of ATP by hexokinase and glucose results in a severe inhibition of medium P, e HOH exchange although extensive intermediate exchange still occurs as shown by...

The oxygen exchange parameters for the hydrolysis of ATP by the F1-ATPase have been determined over a 140,000-fold range of ATP concentrations and a 5,000-fold range of reaction velocity. The average number of water oxygens incorporated into each Pi product ranges from a limit of about 1.02 at saturating ATP concentrations to a limit of about 3.97 at very low ATP concentrations. The latter valu...

The kinase Akt plays a central role as a regulator of multiple growth factor input signals, thus making it an attractive anticancer drug target. A-443654 is an ATP-competitive Akt inhibitor. Unexpectedly, treatment of cells with A-443654 causes paradoxical hyperphosphorylation of Akt at its two regulatory sites (Thr308 and Ser473). We explored whether inhibitor-induced hyperphosphorylation of A...

Abstract Tripartite efflux pumps built around ATP-binding cassette (ABC) transporters are membrane protein machineries that perform vectorial export of a large variety drugs and virulence factors from Gram negative bacteria, using ATP-hydrolysis as energy source. Determining the number ATP molecules consumed per transport cycle is essential to understanding efficiency substrate transport. Using...

The principal catalytic factor in the activation of tyrosine by the tyrosyl-tRNA synthetase is found to be improved binding of ATP in the transition state. The activation reaction involves the attack of the tyrosyl carboxylate on the alpha-phosphate group of ATP to generate a pentacoordinate transition state. Model building of this complex located a binding site for the gamma-phosphate group of...

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel in the ATP binding cassette (ABC) transporter family. Like other ABC transporters, it can hydrolyze ATP. Yet while ATP hydrolysis influences channel gating, it has long seemed puzzling that CFTR would require this reaction because anions flow passively through CFTR. Moreover, no other ion channel is known to require ...

To better understand the mechanism of ligand binding and ligand-induced conformational change, the crystal structure of apoenzyme catalytic (C) subunit of adenosine-3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) was solved. The apoenzyme structure (Apo) provides a snapshot of the enzyme in the first step of the catalytic cycle, and in this unliganded form the PKA C subunit ado...

Cytoplasmic dynein is a homodimeric microtubule (MT) motor protein responsible for most MT minus-end-directed motility. Dynein contains four AAA+ ATPases (AAA: ATPase associated with various cellular activities) per motor domain (AAA1-4). The main site of ATP hydrolysis, AAA1, is the only site considered by most dynein motility models. However, it remains unclear how ATPase activity and MT bind...