C-terminal domains of Escherichia coli topoisomerase I belong to the zinc-ribbon superfamily

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Abstract

Detection of remote evolutionary connections is increasingly difficult with sequence and structural divergence. A combination of sequence and structural analysis, in which statistically supported sequence similarity had a crucial impact, revealed that Escherichia coli topoisomerase I C-terminal fragment is evolutionarily related to the three tetracysteine zinc-binding domains of the enzyme. Spatial structure analysis of this C-terminal fragment indicates that it consists of two structurally similar domains and suggests homology between them. Sequence similarity between the zinc-binding domains of type Ia topoisomerases and transcription regulators of known spatial structure helps to conclude that E. coli topo I contains five copies of a zinc ribbon domain at the C terminus. Two of these domains, corresponding to the C-terminal fragment, lost their cysteine residues and are probably not able to bind zinc. Present analyses lead to the classification of the C-terminal fragment of E. coli topoisomerase I as a member of zinc ribbon superfamily, despite the absence of zinc-binding sites. (C) 2000 Academic Press.

Original languageEnglish (US)
Pages (from-to)1165-1177
Number of pages13
JournalJournal of Molecular Biology
Volume299
Issue number5
DOIs
StatePublished - Jun 23 2000

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Keywords

  • Classification
  • Fold recognition
  • Molecular evolution
  • Protein structure
  • Sequence similarity
  • Transcription regulators

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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