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Multiple forms and cellular localization of Drosophila DNA topoisomerase II.

1986; Elsevier BV; Volume: 261; Issue: 17 Linguagem: Inglês

10.1016/s0021-9258(19)57512-3

1083-351X

Renu A. Heller, Earl R. Shelton, V. Dietrich, Sarah C. R. Elgin, Douglas L. Brutlag,

Protist diversity and phylogeny

Purified type I1 topoisomerase from Drosophila meyotic type I1 topoisomerase, DNA gyrase, is to induce negative lanogaster embryos was reported earlier to contain a writhes in DNA.The eukaryotic enzymes, on the other hand, major Pob'PePtide of 166,000 daltons and several relax both positively and negatively supercoiled DNA (1,2).m d l e r Peptides between 132,000 and 145,000 dal-Another major difference between the eukaryotic and protons (Shelton, E. R., Osheroff, N. and D* L. karyotic type I1 topoisomerases is their subunit structure.(1983) J-B i d .Chem. 258, 9530-9535).Using Purim DNA gyrase is a tetramer 'containing two A subunits of fied topoisomerase I1 we have raised antibodies against 105,000 daltons and two subunits of g5,,oo daltons.Bath the 132,000-166,000-dalton cluster of polypeptides.these polypeptides are also present in embryos imme-each mediates a different part of the topoisomerase reaction.diately upon lysis.Using antigen-dfinity purified an-The A subunit catalyzes DNA strand cleavage and is inhibited tibody from the cluster of purified topoisomerase 11 by the antibiotic nalidixic acid.The B subunit is responsible antigens, we have also &=overed several smaller poly-for the hydrolysis of ATP, an essential cofactor for all type I1 peptides in the molecular size range of 30,000-40,000 topoisomerases and is sensitive to the antibiotic novobiocin daltons in embryo extracts.These observations suggest (1,2).We have shown that the Drosophila DNA topoisomerthe presence of multiple forms of DNA topoisomerases ase I1 is most likely a homodimer of 166,000-dalton subunits, in the cell.In addition, W e demonstrate that purified possesses both DNA and ATP binding sites, and is sensitive topoisomerase 'I antigens expressed by 'gt structures have been observed from other eukaryotic orgatopoisomerase 11 recombinants (Goto, T. and Wang, J. nisms with the HeLa cell enzyme being a homodimer of C. (1984) Cell 36, 1073-1080) establishing a struczymes.of a 150,000-dalton polypeptide (6).We show below that the Antibody preparations were also used to localize the yeast and Drosophila topoisomerase 11 are also related antidistribution of topoisomerase 11 in polytene nuclei.In genically as determined by using affinity-purified antibodies contrast with the distributi0.n of topoisomerase I which directed at the Drosophila topoisomerase 11. is located primarily at puffs, the Dl'osophila topoisom-In addition to the major polypeptide of 166,000 daltons, the