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Literature summary for 5.6.2.1 extracted from

  • Narula, G.; Tse-Dinh, Y.C.
    Residues of E. coli topoisomerase I conserved for interaction with a specific cytosine base to facilitate DNA cleavage (2012), Nucleic Acids Res., 40, 9233-9243.
    View publication on PubMedView publication on EuropePMC

Protein Variants

Protein Variants Comment Organism
additional information dissociation constants obtained for binding of wild-type EcTOP1, R169A, R173A and Y177S mutant enzymes to 3'-labeled 59 base hairpin oligonucleotide substrates, Oligo C, Oligo A and Oligo G, overview Escherichia coli
R169 site-directed mutagenesis, the mutant shows reduced DNA cleavage and relaxation activity compared to the wild-type enzyme, the mutation to alanine changesd the selectivity of the enzyme for the base at the -4 position from a cytosine to an adenine Escherichia coli
R173A site-directed mutagenesis, the mutant displays similar sequence selectivity as the wild-type enzyme, but weaker cleavage and relaxation activity Escherichia coli
Y177A site-directed mutagenesis, inactive mutant Escherichia coli
Y177S site-directed mutagenesis, inactive mutant Escherichia coli

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information dissociation constants obtained for binding of wild-type EcTOP1, R169A, R173A and Y177S mutant enzymes to 3'-labeled 59 base hairpin oligonucleotide substrates, Oligo C, Oligo A and Oligo G, overview Escherichia coli

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ required Escherichia coli

Organism

Organism UniProt Comment Textmining
Escherichia coli
-
-
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
additional information cleavage of 556 base single-stranded DNA substrate supercoiled pBAD/thio plasmid, and cleavage and religation of 59 base hairpin oligonucleotide substrates Escherichia coli ?
-
?

Synonyms

Synonyms Comment Organism
Topoisomerase I
-
Escherichia coli

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
37
-
assay at Escherichia coli

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8
-
assay at Escherichia coli

General Information

General Information Comment Organism
additional information residues R169, R173 and Y177 work together to interact with a cytosine base at the -4 position to facilitate DNA cleavage. R169 and R173 interact with the cytosine base at the -4 position via hydrogen bonds while the phenol ring of Y177 wedges between the bases at the -4 and the -5 position Escherichia coli