Abutilon mosaic geminivirus double-stranded DNA is packed into minichromosomes.

An intermediate form of Abutilon mosaic geminivirus, a complex of viral double-stranded DNA (dsDNA) and protein, was characterized by two different techniques. Cesium sulphate gradient centrifugation was used to show that the majority of this form comigrates with host chromatin. Micrococcus nuclease digestion experiments with isolated nuclei demonstrated that the viral dsDNA is organized in a manner comparable to that of host nucleosomes. Results from a previous electron microscopical work (Abouzid, A. M., Frischmuth, T., and H. Jeske, 1988, Mol. Gen. Genet. 212, 252-258) suggested to us that a part of the viral dsDNA must be free of nucleosomes. Whether this nucleosome-free space corresponds to the intergenic region which contains most of the promotor sequences and the putative origin of replication is discussed.