Journal of Molecular Biology
Mutation in Cys662 ofEscherichia coliDNA Topoisomerase I Confers Temperature Sensitivity and Change in DNA Cleavage Selectivity
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Cited by (22)
Crystal Structure of Full Length Topoisomerase I from Thermotoga maritima
2006, Journal of Molecular BiologyViability of Escherichia coli topA mutants lacking DNA topoisomerase I
2005, Journal of Biological ChemistryCitation Excerpt :The chloramphenicol resistance marker cam was amplified from pACYC184 (supplied by New England Biolabs) by PCR in the presence of primers that would add SphI sites to both ends of a 1.41-kb DNA product; the inducible lac promoter used in the construction of one class of derivatives was obtained from pJW312 as a HindIII-EcoRI fragment (30). Codon substitutions within the topA region were done by replacing appropriate DNA segments by the corresponding segments containing the alterations L5F C662H (36) or G65N W79S (37). Various pRM4-N derivatives were linearized by digestion with NotI.
Thermotoga maritima-Escherichia coli chimeric topoisomerases: Answers about involvement of the carboxyl-terminal domain in DNA topoisomerase
2004, Journal of Biological ChemistryCitation Excerpt :Another argument for an important role of the carboxyl-terminal domains in substrate recognition is that cleavage specificities of the core domains TmTop65 and EcTop67 are different from those of the full-length corresponding topoisomerases. Previous results concerning the role of the carboxyl-terminal part in the reaction mechanism of E. coli topoisomerase I are not clear; consistent with our results, it has been shown that the enzyme, mutated in one of the three zinc fingers located in the carboxyl-terminal part of the protein, changed its cleavage site specificity (19). However, our conclusions differ from that of Ahumada et al. (20) who showed that E. coli Top67 had the same sequence and structure selectivity for DNA cleavage as the full-length enzyme.
Enzymes That Cleave and Religate DNA at High Temperature: The Same Story with Different Actors
2003, Progress in Nucleic Acid Research and Molecular BiologyOn the molecular basis of the thermal sensitivity of an Escherichia coli topA mutant
2002, Journal of Biological ChemistryHyperthermophilic topoisomerase I from Thermotoga maritima: A very efficient enzyme that functions independently of zinc binding
2001, Journal of Biological ChemistryCitation Excerpt :These results contrast with those found forE. coli topoisomerase I, in which zinc binding to the three tetracysteine motifs is required for DNA relaxation activity (13, 14) and disruption of the second zinc motif deeply affects thermal stability and cleavage specificity (18). Indeed, it was proposed that the zinc binding domain would contribute to the stabilization of the association of the 3′-end of the cleaved DNA with topoisomerase I and would assist the passage of uncleaved strand across the break (14, 34).
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Abbreviations used: ICP, inductively coupled plasma; PAR, 4-(2-pyridylazo)resorcinol; PMPS,p-(hydroxymercuri)benzenesulfonate.