EFFECT OF GLYCEROL ON THE AFFINITY OF DNAA PROTEIN FOR ATP IN THE PRESENCE OF CARDIOLIPIN

Acidic phospholipids, such as cardiolipin, decrease the affinity of Dn aA protein for adenine nucleotides and can activate the inactive form of DnaA protein in vitro. In this study, we examined the effect of gly cerol on the affinity of DnaA protein for ATP in the presence of cardi olipin, High concentrations of glycerol (34%) restored the affinity of DnaA protein for ATP, which was decreased by cardiolipin. Glycerol in hibited the binding of cardiolipin with DnaA protein, Glycerol had lit tle effect on membrane fluidity, which is essential for the interactio n between cardiolipin and DnaA protein, whereas it increased the K-d v alue of DnaA protein for ATP in the absence of cardiolipin, These resu lts suggest that glycerol causes DnaA protein to become insensitive as to the interaction with cardiolipin by changing the conformation of t he protein without altering the physical nature of the phospholipid.