1cy9
CRYSTAL STRUCTURE OF THE 30 KDA FRAGMENT OF E. COLI DNA TOPOISOMERASE I. MONOCLINIC FORMCRYSTAL STRUCTURE OF THE 30 KDA FRAGMENT OF E. COLI DNA TOPOISOMERASE I. MONOCLINIC FORM
Structural highlights
Function[TOP1_ECOLI] Releases the supercoiling and torsional tension of DNA, which is introduced during the DNA replication and transcription, by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 3'-OH DNA strand. The free DNA strand then undergoes passage around the unbroken strand, thus removing DNA supercoils. Finally, in the religation step, the DNA 3'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedDNA 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. Conformational changes in E. coli DNA topoisomerase I.,Feinberg H, Lima CD, Mondragon A Nat Struct Biol. 1999 Oct;6(10):918-22. PMID:10504724[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
|
| ||||||||||||||||||