title: Topoisomerase IB-DNA interactions: X marks the spot.
abstract: The observation made twenty years ago that type IB topoisomerases bound DNA helix-helix juxtapositions was unexpected, given the controlled helical rotation mechanism of the enzyme. In this issue, Patel et al. (2010) provide an elegant structural explanation for this interaction.
authors.affiliation: Department of Molecular Virology and Microbiology, Verna and Marrs McClean Department of Biochemistry and Molecular Biology, Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Lynn
authors.initials: L
authors.lastname: Zechiedrich
authors.forename: Neil
authors.initials: N
authors.lastname: Osheroff