Altered Conformational Effects of Naturally Acetylated Histone f2al (IV) in f2al-Deoxyribonucleic Acid Complexes

The glycine-arginine-rich (f2al) histone from calf thymus was separated into its naturally occurring nonacetylated, monoacetylated and di- and/or triacetylated subfractions. Reconstituted complexes of calf thymus DNA with each of these subfractions were examined by means of circular dichroism. Significant differences in conformational properties were found. With f2al containing e-N-acetyllysine at residue 16, the circular dichroism changes characteristic of nonacetylated f2al-DNA complexes in 0.14 m NaF were nearly abolished. Multiacetylated f2al caused a different type of circular dichroism change when incorporated into complexes with DNA. These observations indicate that the monoacetylated f2al histone is less effective than nonacetylated in producing conformational distortions of DNA, which may be relevant for a mechanism of genetic regulation or for the control of chromatin structure.