HISTONE H1 AND CORE HISTONES IN LEISHMANIA AND CRITHIDIA - COMPARISONWITH TRYPANOSOMA

The Trypanosomatidae family is characterized by flagellated protozoa p resenting a kinetoplast. Several genera of this family contain species that are pathogenic to man and domestic animals. Their chromatin is n ot condensed into chromosomes during cell division. As a contribution to the understanding of basic aspects of their genome organization, we present a systematic characterization of the histones from three gene ra of the Trypanosomatidae family. Crithidia fasciculata and Leishmani a mexicana show core nucleosomal histones with electrophoretic mobilit ies both similar to and different from those of Trypanosoma cruzi and higher eukaryotes. Another protein is extracted from the chromatin of these organisms by procedures designed to purify histone H1. This prot ein presents elution profiles by HPLC and amino acid composition of hi stone ill. Considering these data and the high mobility of this protei n in Triton-acetic acid-urea-polyacrylamide gel electrophoresis, as we ll as its position relative to the nucleosomal core histones in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we postulate that Crithidia and Leishmania possess a histone H1 shorter than that of hi gher eukaryotes as we have previously shown to be the case for T. cruz i. The possible presence of a shorter histone H1 in these trypanosomat ids may explain the absence of chromatin condensation during cell divi sion in these flagellates. (C) 1996 Academic Press, Inc.