Characterization of a unique type IA topoisomerase in Bacillus cereus.
Bacillus cereus topoisomerase IIIbeta (bcTopo IIIbeta) has been cloned, overexpressed and biochemically characterized. This enzyme exhibits 64% and 33% sequence identity to Bacillus subtilis topoisomerase III (bsTopo III) and Escherichia coli topoisomerase III (ecTopo III) respectively. The enzymatic properties of bcTopo IIIbeta differ substantially from other bacterial type IA topoisomerases, including E. coli type IA topoisomerases and B. cereus topoisomerase I (bcTopo I) and IIIalpha (bcTopo IIIalpha). bcTopo IIIbeta only partially relaxes negatively supercoiled DNA and appears incapable of generating fully relaxed topoisomers. In contrast to ecTopo III and bcTopo IIIalpha, bcTopo IIIbeta is not a decatenase. bcTopo IIIbeta is unable to compensate the loss of ecTopo III in vivo. Therefore, bcTopo IIIbeta is a unique prokaryotic type IA topoisomerase that is different from previously characterized topoisomerases.
Li
Zhiyu
Z
Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, USA.
Hiasa
Hiroshi
H
DiGate
Russell
R
D000595:Amino Acid Sequence; D001409:Bacillus cereus / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D004264:DNA Topoisomerases, Type I / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016415:Sequence Alignment
D004278:DNA, Superhelical; D007527:Isoenzymes; D004264:DNA Topoisomerases, Type I