Li Z, Mondragón A, Hiasa H, Marians K J, DiGate R J
Department of Pharmaceutical Sciences, University of Maryland, Baltimore School of Pharmacy, 20 North Pine Street, Baltimore, MD 21201, USA.
Mol Microbiol. 2000 Feb;35(4):888-95. doi: 10.1046/j.1365-2958.2000.01763.x.
A 17-amino-acid residue domain has been identified in Escherichia coli DNA topoisomerase III (Topo III) that is essential for Topo III-mediated resolution of DNA replication intermediates in vitro. Deletion of this domain reduced Topo III-catalysed resolution of DNA replication intermediates and decatenation of multiply linked plasmid DNA dimers by four orders of magnitude, whereas reducing Topo III-catalysed relaxation of negatively supercoiled DNA substrates only 20-fold. The presence of this domain has been detected in multiple plasmid-encoded topoisomerases, raising the possibility that these enzymes may also be decatenases.
在大肠杆菌DNA拓扑异构酶III（Topo III）中已鉴定出一个17个氨基酸残基的结构域，该结构域对于Topo III在体外介导的DNA复制中间体的拆分至关重要。缺失该结构域会使Topo III催化的DNA复制中间体的拆分以及多链连接的质粒DNA二聚体的解连环作用降低四个数量级，而仅使Topo III催化的负超螺旋DNA底物的松弛作用降低20倍。在多种质粒编码的拓扑异构酶中均检测到了该结构域的存在，这增加了这些酶也可能是解连环酶的可能性。
