title: Conformational changes in E. coli DNA topoisomerase I.
abstract: DNA topoisomerases are the enzymes responsible for maintaining the topological states of DNA. In order to change the topology of DNA, topoisomerases pass one or two DNA strands through transient single or double strand breaks in the DNA phosphodiester backbone. It has been proposed that both type IA and type II enzymes change conformation dramatically during the reaction cycle in order to accomplish these transformations. In the case of Escherichia coli DNA topoisomerase I, it has been suggested that a 30 kDa fragment moves away from the rest of the protein to create an entrance into the central hole in the protein. Structures of the 30 kDa fragment reveal that indeed this fragment can change conformation significantly. The fragment is composed of two domains, and while the domains themselves remain largely unchanged, their relative arrangement can change dramatically.
authors.affiliation: Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, Illinois 60208, USA.
authors.forename: H
authors.initials: H
authors.lastname: Feinberg
authors.forename: C D
authors.initials: CD
authors.lastname: Lima
authors.forename: A
authors.initials: A
authors.lastname: Mondragón
mesh_terms: D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D004264:DNA Topoisomerases, Type I / Q000737:chemistry* / Q000378:metabolism*; D004583:Electrons; D004926:Escherichia coli / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D014443:Tyrosine / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D014443:Tyrosine; D004264:DNA Topoisomerases, Type I