In vivo topoisomerase II cleavage of the Drosophila histone and satellite III repeats: DNA sequence and structural characteristics

• Published in: The EMBO journal 1992-02, Vol.11 (2), p.705-716
• Main Authors: Kas, E, Laemmli, U.K
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Animals; antibiotics; Base Sequence; Biological and medical sciences; Blotting, Southern; Cell Line; Cell Nucleus - metabolism; centromeres; chromomycin; Chromomycins - pharmacology; cleavage sites; distamycin; Distamycins - pharmacology; DNA - genetics; DNA - metabolism; DNA conformation; DNA topoisomerase (ATP-hydrolysing); DNA Topoisomerases, Type II - metabolism; DNA, Satellite - genetics; DNA, Satellite - metabolism; Drosophila; Drosophila melanogaster; Drosophila melanogaster - genetics; enzyme activity; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; histone gene loop; histones; Histones - genetics; Hot Temperature; Isomerases; Molecular Sequence Data; multiple genes; nucleosome linker regions; nucleotide sequences; repetitive sequences; Repetitive Sequences, Nucleic Acid; satellite DNA; scaffold-associated regions; Substrate Specificity
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1992.tb05103.x

We have identified two classes of in vivo topoisomerase H cleavage sites in the Drosophila histone gene repeat. One class co-localizes with DNase I-hypersensitive regions and another novel class maps to a subset of consecutive nucleosome linker sites in the scaffold-associated region (SAR) of the histone gene loop. Prominent topoisomerase II cleavage is also observed in one of the linker regions of the two nucleosomes spanning satellite III, a centromeric SAR-like DNA sequence with a repeat length of 359 bp. At the sequence level, in vivo topoisomerase II cleavage is highly site specific. Comparison of 10 nucleosome linker sites defines an in vivo cleavage sequence whose major characteristic is a prominent GC-rich core. These GC-rich cleavage sites are flanked by extensive arrays of oligo(dA) . oligo(dT) tracts characteristic of SAR sequences. Treatment of cells with distamycin selectively enhances cleavage at nucleosome linker sites of the SAR and satellite regions, suggesting that AT-rich sequences flanking cleavage sites may be involved in determining topoisomerase H activity in the cell. These observations provide evidence for the association of topoisomerase H with SARS in vivo.