PMID:16192570
| Citation |
Li, Z, Hiasa, H and DiGate, R (2005) Bacillus cereus DNA topoisomerase I and IIIalpha: purification, characterization and complementation of Escherichia coli TopoIII activity. Nucleic Acids Res. 33:5415-25 |
|---|---|
| Abstract |
The Bacillus cereus genome possesses three type IA topoisomerase genes. These genes, encoding DNA topoisomerase I and IIIalpha (bcTopo I, bcTopo IIIalpha), have been cloned into T7 RNA polymerase-regulated plasmid expression vectors and the enzymes have been overexpressed, purified and characterized. The proteins exhibit similar biochemical activity to their Escherichia coli counterparts, DNA topoisomerase I and III (ecTopo I, ecTopo III). bcTopo I is capable of efficiently relaxing negatively supercoiled DNA in the presence of Mg2+ but does not possess an efficient DNA decatenation activity. bcTopo IIIalpha is an active topoisomerase that is capable of relaxing supercoiled DNA at a broad range of Mg2+ concentrations; however, its DNA relaxation activity is not as efficient as that of bcTopo I. In addition, bcTopo III is a potent DNA decatenase that resolves oriC-based plasmid replication intermediates in vitro. Interestingly, bcTopo I and bcTopo IIIalpha are both able to compensate for the loss of ecTopo III in E.coli cells that lack ecTopo I. In contrast, ecTopo I cannot substitute for ecTopo III under these conditions. |
| Links |
PubMed PMC1236973 Online version:10.1093/nar/gki846 |
| Keywords |
Bacillus cereus/enzymology; Bacillus cereus/genetics; Base Sequence; Binding Sites; DNA/chemistry; DNA/metabolism; DNA Topoisomerases, Type I/genetics; DNA Topoisomerases, Type I/isolation & purification; DNA Topoisomerases, Type I/metabolism; DNA, Single-Stranded/metabolism; Escherichia coli/enzymology; Genetic Complementation Test; Molecular Sequence Data; Substrate Specificity |
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