Beschreibung:
<jats:p>
The major sensor kinase controlling the initiation of
development in
<jats:italic>Bacillus subtilis</jats:italic>
, KinA, functions
by activating the phosphorelay signal-transduction system in response
to as yet unknown signal ligands. KinA contains, within its
amino-terminal signal-sensing region, three PAS domains that, in other
proteins, are known to be involved in sensing changes in oxygen
concentration and redox potential among other functions. The most
amino-terminal PAS domain, PAS-A, was found to bind ATP and catalyze
exchange of phosphate between ATP and nucleoside diphosphates. A
cysteine-to-alanine mutation in PAS-A increased the affinity for ATP
5-fold, decreased the exchange reaction 2-fold, and stimulated
KinA-dependent sporulation. A model for the role of ATP and the
exchange reaction in the PAS domain in sensor kinase signal
transduction is presented in which the free energy of nucleotide
hydrolysis drives the conformational changes that activate or
deactivate the sensor kinase in response to signal ligand binding.
</jats:p>