1cy4
From Proteopedia
COMPLEX OF E.COLI DNA TOPOISOMERASE I WITH 5'pTpTpTp3'
Structural highlights
FunctionTOP1_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 controlling and maintaining the topological states of DNA. Type IA enzymes work by transiently breaking the phosphodiester backbone of one strand to allow passage of another strand through the break. The protein has to perform complex rearrangements of the DNA, and hence it is likely that different regions of the enzyme bind DNA with different affinities. In order to identify some of the DNA binding sites in the protein, we have solved the structures of several complexes of the 67 kDa N-terminal fragment of Escherichia coli DNA topoisomerase I with mono- and trinucleotides. There are five different binding sites in the complexes, one of which is adjacent to the active site. Two other sites are in the central hole of the protein and may represent general DNA binding regions. The positions of these sites allow us to identify different DNA binding regions and to understand their possible roles in the catalytic cycle. Protein-nucleotide interactions in E. coli DNA topoisomerase I.,Feinberg H, Changela A, Mondragon A Nat Struct Biol. 1999 Oct;6(10):961-8. PMID:10504732[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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