PRESENCE OF AN UNUSUALLY HIGH-CONCENTRATION OF AN UBIQUITINATED HISTONE-LIKE PROTEIN IN TRYPANOSOMA-CRUZI

The conjugation of ubiquitin to histones H2A and H2B has been establis hed in higher eukaryotes and has been related to changes in chromatin organization. In Trypanosoma cruzi, no condensation of chromatin occur s during mitosis. In order to determine the presence of histone ubiqui tination in T. cruzi epimastigotes, histones were extracted from chrom atin and analyzed by three electrophoretic systems: acid-urea, triton- acid-urea and sodium-dodecylsulphate polyacrylamide gel. The immunoche mical detection of ubiquitin-histone conjugates by Western blotting sh owed a strong reaction with a slow migrating band of M-r 19 kDa. The h igh percentage of ubiquitin-histone conjugates present in T. cruzi chr omatin may be related to the inability of this parasite to condense ch romatin into a 30 nm fiber. (C) 1997 Wiley-Liss, Inc.