McMillan DGG
ATP binding by an F1Fo ATP synthase ε subunit is pH dependent, suggesting a diversity of ε subunit functional regulation in bacteria
F-type ATP synthases synthesize ATP, the universal energy source in most living cells. The enzyme consists of a membrane embedded Fo domain, which is composed of the membrane embedded proteolipid ring (c subunits), the collar-like a subunit which is asymmetrically wrapped around the c-ring, and the b subunit dimer which links the membrane embedded c-subunit ring and a subunit to the F1 domain.
ReadA second shell residue modulates a conserved ATP-binding site with radically different affinities for ATP
Prediction of ligand binding and design of new function in enzymes is a time-consuming and expensive process. Crystallography gives the impression that proteins adopt a fixed shape, yet enzymes are functionally dynamic. Molecular dynamics offers the possibility of probing protein movement while predicting ligand binding. Accordingly, we choose the bacterial F1Fo ATP synthase ε subunit to unravel why ATP affinity by ε subunits from Bacillus subtilis and Bacillus PS3 differs ~500-fold, despite sharing identical sequences at the ATP-binding site.
ReadThe Molecular Basis for Purine Binding Selectivity in the Bacterial ATP Synthase ϵ Subunit
The ϵ subunit of ATP synthases has been proposed to regulate ATP hydrolysis in bacteria. Prevailing evidence supports the notion that when the ATP concentration falls below a certain threshold, the ϵ subunit changes its conformation from a non‐inhibitory down‐state to an extended up‐state that then inhibits enzymatic ATP hydrolysis by binding to the catalytic domain.
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