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Partial amino acid sequence and functional aspects of histone H1 proteins in Trypanosoma brucei brucei
Author(s) -
Burri Markus,
Schlimme Wolfram,
Betschart Bruno,
Lindner Herbert,
Kämpfer Urs,
Schaller Johann,
Hecker Hermann
Publication year - 1995
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1016/0248-4900(96)89928-x
Subject(s) - histone h1 , trypanosoma brucei , biology , chromatin , histone , biochemistry , histone h2a , histone modifying enzymes , microbiology and biotechnology , dna , gene
Summary— Trypanosoma brucei brucei , a protozoan parasite of wild and domestic animals in Africa, is related to the pathogenic agent of human sleeping sickness. Four H1 histone proteins were isolated from nuclei of procyclic culture forms and cleaved with proteases. Amino acid sequence analysis of purified fragments indicated the presence of variants which displayed sequence identities as compared to the C‐terminal domain of human H1. Substitutions of amino acids and posttranslational modifications of the histones in iT b brucei H1 may influence protein conformation and histone‐histone as well as histone‐DNA interactions in the chromatin of the parasite. Digestion of soluble chromatin with immobilized trypsin at low and high ionic strengths indicated an internal localization of H1 in the condensed chromatin. The influence of histone H1 of T b brucei on the compaction pattern of the chromatin was investigated by dissociation and reconstitution experiments. Electron microscopy revealed that trypanosome H1 was able to induce condensation of the chromatin of the parasite and of rat liver into dense tangles. After dephosphorylation of H1, 30 nm fibers were induced in rat liver chromatin, while the resulting fibers were distinctly thinner in T b brucei . It can be concluded that the absence of 30 nm fibers in T b brucei chromatin cannot be explained by the divergent variants and posttranslational phosphorylations of H1 only but rather by the influence of both, the divergent core histones, previously described, and H1 properties.