Mapping the active-site tyrosine of vaccinia virus DNA topoisomerase I Journal Article


Authors: Shuman, S.; Kane, E. M.; Morham, S. G.
Article Title: Mapping the active-site tyrosine of vaccinia virus DNA topoisomerase I
Abstract: Site-directed mutagenesis of the vaccinia virus gene encoding a type I DNA topoisomerase implicates Tyr-274 as the active-site residue that forms a covalent adduct with DNA during cycles of DNA-strand breakage and reunion. Replacement of Tyr-274 by phenylalanine results in loss of the ability of the enzyme to relax negatively supercoiled DNA as well as to form the covalent DNA-protein intermediate. Substitution of phenylalanine for tyrosine at nine other sites in the protein has no apparent effect on enzyme activity. Amino acid sequence alignment reveals Tyr-274 to be homologous to Tyr-727 and Tyr-771, respectively, of the type I topoisomerases from Saccharomyces cerevisiae and Saccharomyces pombe; Tyr-727 and Tyr-771 have been shown to represent the active-site tyrosines of those enzymes. Sequence comparison of the active-site regions defines a motif Ser-Lys-Xaa-Xaa-Tyr common to the viral and cellular type I topoisomerases, including the human enzyme.
Keywords: mutation; nonhuman; comparative study; gene expression; structure activity relation; tyrosine; cloning, molecular; molecular sequence data; saccharomyces cerevisiae; escherichia coli; recombinant proteins; vaccinia virus; base sequence; binding sites; codon; site directed mutagenesis; phenylalanine; dna topoisomerase; dna topoisomerases, type i; enzyme active site; covalent catalysis; vaccinia; virus dna; saccharomyces; saccharomyces pombe; priority journal; article; support, u.s. gov't, p.h.s.; genes, structural, viral; tyrosyl phosphodiester linkage; yeast topoisomerase
Journal Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 86
Issue: 24
ISSN: 0027-8424
Publisher: National Academy of Sciences  
Date Published: 1989-12-01
Start Page: 9793
End Page: 9797
Language: English
DOI: 10.1073/pnas.86.24.9793
PUBMED: 2557629
PROVIDER: scopus
PMCID: PMC298588
DOI/URL:
Notes: Article -- Export Date: 14 April 2020 -- Source: Scopus
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  1. Stewart H Shuman
    546 Shuman