Nuclease sensitivity of adenovirus type 2 chromatin in lytic infection.

We have investigated the sensitivity of adenovirus type 2 naked DNA and chromatin at 5 h and 20 h after infection to digestion by DNase I, micrococcal nuclease and endogenous nuclease between map coordinates 11.3 and 18.0 (SmaI-F fragment) using a terminal labelling method. Infected cell nuclei were gently digested with nucleases, DNA was extracted and digested to completion with SmaI and the fragments shorter than the SmaI-F fragment mapped by hybridization with a 708 base pair probe co-terminal with the SmaI-F fragment. Early chromatin contained hypersensitive sites at 16.0 and 14.3. These sites became minor cleavage sites in late chromatin and new hypersensitive sites appeared at 13.5 and 13.0. The change in the location of the hypersensitive sites in the course of infection correlated with the early to late switch in the transcription pattern in this region and the early to late change in the overall structure of adenovirus chromatin.