Regulation of histone acetyltransferase activity during the development of Artemia salina,: Characterization of an inhibitor in nauplius larvae

Histone acetyltransferase activity was studied in 1 M KCl extracts from nuclear preparations of Artemia salina. The requirements for optimal activity included a slightly alkaline pH and the absence of mono- and divalent cations. Marked differences in histone saturation kinetics were observed in crude extract from early and late developmental stages. The sigmoidal-type curve observed in nauplii was shown to arise from the presence in these crude extracts of an inhibitor of acetyltransferase activity. Serial substrate-saturation studies with crude acetyltransferase preparations indicate accumulation of inhibitor at times of development, associated with a rapid increase in histone acetyltransferase activity. On the basis of its susceptibility to enzymatic hydrolysis and its gel-filtration behavior, the inhibitor was characterized as a small DNA sequence. Comparative studies of the Artemia inhibitor and sonicated calf thymus DNA indicate that in both cases the inhibition proceeds through a histone-DNA interaction that renders the histone inaccessible to the acetyltransferase. These studies also revealed marked differences in reversibility by protamines and in specificity for histone fractions between the inhibitor from Artemia and DNA from other sources.