title: Topoisomerase from Ustilago maydis forms a covalent complex with single-stranded DNA through a phosphodiester bond to tyrosine.
abstract: Highly purified topoisomerase from Ustilago breaks single-stranded DNA, forming a complex with protein covalently bound to the DNA. Methods used to detect the complexes include a nitrocellulose filter assay, electrophoresis of the DNA-protein complex in agarose gels containing alkali, and isolation of the complex after removal of all but a small oligonucleotide fragment bound to the protein. The linkage of the Ustilago topoisomerase is to the 3' end of the broken strand of DNA. The DNA-protein complex formed is through a phosphodiester bond to tyrosine.
mesh_terms: D001487:Basidiomycota / Q000201:enzymology*; D001665:Binding Sites; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D007700:Kinetics; D011485:Protein Binding; D013379:Substrate Specificity; D014443:Tyrosine; D014588:Ustilago / Q000201:enzymology*
chemical_list: D004277:DNA, Single-Stranded; D014443:Tyrosine; D004264:DNA Topoisomerases, Type I