A Universal Type IA Topoisomerase Fold

A class of enzymes, called DNA topoisomerases, is responsible for controlling the topological state of cellular DNA. Among these, type IA topoisomerases form a vast family that is present in all living organisms, including higher eukaryotes, in which they play important roles in genome stability. Th...

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Published inJournal of molecular biology Vol. 359; no. 3; pp. 805 - 812
Main Authors Duguet, Michel, Serre, Marie-Claude, Bouthier de La Tour, Claire
Format Journal Article
LanguageEnglish
Published England Elsevier Ltd 09.06.2006
Elsevier
Subjects
Amino Acid Sequence
Crystallography, X-Ray
DNA Topoisomerases, Type I - chemistry
evolution
Models, Molecular
Molecular Sequence Data
Phylogeny
Protein Conformation
Protein Folding
Sequence Analysis, Protein
structural fold
Thermotoga maritima
Thermotoga maritima - chemistry
topoisomerase IA
XXX
topoisomerase IA
evolution
structural fold
Thermotoga maritima
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Summary:A class of enzymes, called DNA topoisomerases, is responsible for controlling the topological state of cellular DNA. Among these, type IA topoisomerases form a vast family that is present in all living organisms, including higher eukaryotes, in which they play important roles in genome stability. The known 3D structures of three of these enzymes indicate that they share a common toroidal architecture. We previously showed that the toroidal structure could be split off from the core enzyme of Thermotoga maritima topoisomerase I by limited proteolysis. This structure is produced by the association of two tandemly repeated elementary folds in a head-to-tail orientation. By using a combination of structural and sequence data analysis, we show that the elementary fold of about 150 amino acid residues, referred to as the topofold, is likely to be present in the whole topoisomerase IA family. Within each enzyme, the successive topofolds share two conserved sequence motifs located at the base of the ring, and referred to as the MI and MII motifs. However, the overall sequences of the folds have largely diverged. By contrast, secondary and tertiary structures appear remarkably conserved. We suggest that this twofold repeat has evolved by gene duplication/fusion from an ancestral topofold.
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ISSN:0022-2836
1089-8638
DOI:10.1016/j.jmb.2006.04.021