Mechanistic study of E. coli DNA topoisomerase I: cleavage of oligonucleotides.

AUTOR(ES)

Tse-Dinh, Y C

RESUMO

E. coli DNA topoisomerase I catalyzes DNA topoisomerization by transiently breaking and rejoining single DNA strands (1). When an enzyme-DNA incubation mixture is treated with alkaline or detergent, DNA strand cleavage occurs, and the enzyme becomes covalently linked to the 5'-phosphoryl end of the cleaved DNA (2). Using oligonucleotides of defined length and sequence composition, this cleavage reaction is utilized to study the mechanism of E. coli DNA topoisomerase I. dA7 is the shortest oligonucleotide tested that can be cleaved by the enzyme. dT8 is the shortest oligo(dT) that can be cleaved. The site of cleavage in both cases is four nucleotides from the 3' end of the oligonucleotide. No cleavage can be observed for oligo(dC) and oligo(dG) of length up to eleven bases long. dC15 and dC16 are cleaved at one tenth or less the efficiency of oligo(dA) and oligo(dT) of comparable length.

Documentos Relacionados

• Recognition sites of eukaryotic DNA topoisomerase I: DNA nucleotide sequencing analysis of topo I cleavage sites on SV40 DNA.
• Distamycin inhibition of topoisomerase I-DNA interaction: a mechanistic analysis.
• Labelling DNA ends with the Klenow fragment of the E. coli DNA polymerase I: a cautionary note.
• Topoisomerase IV, alone, unknots DNA in E. coli
• Analysis of nuclear factor I binding to DNA using degenerate oligonucleotides.