title: Organization of telomeric and subtelomeric chromatin in the higher plant Nicotiana tabacum.
abstract: We have examined the structure and chromatin organization of telomeres in Nicotiana tabacum. In tobacco the blocks of simple telomeric repeats (TT-TAGGG)n are many times larger than in other plants, e.g., Arabidopsis thaliana or tomato. They are resolved as multiple fragments 60-160 kb in size (in most cases 90-130 kb) on pulsed-field gel electrophoresis (PFGE) of restriction endonuclease-digested DNA. The major subtelomeric repeat of the HRS60 family forms large homogeneous blocks of a basic 180 bp motif having comparable lengths. Micrococcal nuclease (MNase) cleaves tobacco telomeric chromatin into subunits with a short repeat length of 157 +/- 5 bp; the subtelomeric heterochromatin characterized by tandemly repeated sequences of the HRS60 family is cut by MNase with a 180 bp periodicity. The monomeric and dimeric particles of telomeric and subtelomeric chromatin differ in sensitivity to MNase treatment: the telomeric particles are readily digested, producing ladders with a periodicity of 7 bp, while the subtelomeric particles appear to be rather resistant to intranucleosomal cleavage. The results presented show apparent similarities in the organization of telomeric chromatin in higher plants and mammals.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno.
authors.forename: J
authors.initials: J
authors.lastname: Fajkus
authors.forename: A
authors.initials: A
authors.lastname: Kovarík
authors.forename: R
authors.initials: R
authors.lastname: Královics
authors.forename: M
authors.initials: M
authors.lastname: Bezdĕk
mesh_terms: D002843:Chromatin / Q000235:genetics*; D018744:DNA, Plant / Q000032:analysis / Q000235:genetics*; D010947:Plants, Toxic; D012091:Repetitive Sequences, Nucleic Acid; D016615:Telomere / Q000235:genetics; D014026:Nicotiana / Q000235:genetics*
chemical_list: D002843:Chromatin; D018744:DNA, Plant