Subunit structure of Trypanosoma cruzi chromatin.

Chromatin of Trypanosoma cruzi epimastigotes was found to be arranged in a subunit structure by the demonstration of (i) nu-bodies, (ii) monomeric and oligomeric DNA fragments, and (iii) four basic nuclear proteins which presumably correspond to the intrinsic protein component of nucleosomes. A discrete core fragment of 140 base pairs and a basic nuclear protein fraction clearly similar to most histones H1 were not detected. In contrast with vertebrate material, the nuclear preparations were physically and enzymatically fragile, the basic proteins showed different mobilities in electrophoresis, but the DNA repeat length was similar. The data are discussed in relation to histone regional charge, histone content, and chromatin condensation.