Calmodulin-like protein from Bacillus subtilis.

The first example of a calmodulin-like activity in a Gram-positive bacterium, Bacillus subtilis, is reported. A calcium ion-dependent, 3', 5' cyclic-AMP phosphodiesterase-stimulating activity was found in the soluble fraction of cell-free extracts of cells sporulating in a chemically-defined medium; activation was reversed by trifluoperazine. The activity was heat stable, bound to phenothiazine-agarose in a calcium ion-dependent manner and was eluted therefrom with buffer containing EGTA, and displaced authentic beef brain calmodulin from its antibody in a radioimmunoassay.