title: Deletion of the topoisomerase III gene in the hyperthermophilic archaeon Sulfolobus islandicus results in slow growth and defects in cell cycle control.
abstract: Topoisomerase III (topo III), a type IA topoisomerase, is widespread in hyperthermophilic archaea. In order to interrogate the in vivo role of archaeal topo III, we constructed and characterized a topo III gene deletion mutant of Sulfolobus islandicus. The mutant was viable but grew more slowly than the wild-type strain, especially in a nutrient-poor medium. Flow cytometry analysis revealed changes of the mutant in growth cycle characteristics including an increase in proportion of cells containing either more than two genome equivalents or less than one genome equivalent in exponentially-growing cultures. As shown by fluorescence microscopy, a fraction of mutant cells in the cultures were drastically enlarged, and at least some of the enlarged cells were apparently capable of resuming cell division. The mutant also shows a different transcriptional profile from that of the wild-type strain. Our results suggest that the enzyme may serve roles in chromosomal segregation and control of the level of supercoiling in the cell.
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Xiyang
authors.initials: X
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Guo
authors.forename: Ling
authors.initials: L
authors.lastname: Deng
authors.forename: Deqin
authors.initials: D
authors.lastname: Feng
authors.forename: Yi
authors.initials: Y
authors.lastname: Ren
authors.forename: Yindi
authors.initials: Y
authors.lastname: Chu
authors.forename: Qunxin
authors.initials: Q
authors.lastname: She
authors.forename: Li
authors.initials: L
authors.lastname: Huang
mesh_terms: D002453:Cell Cycle / Q000235:genetics*; D002455:Cell Division / Q000235:genetics; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D016944:Sulfolobus / Q000235:genetics* / Q000254:growth & development*; D014158:Transcription, Genetic
chemical_list: D004264:DNA Topoisomerases, Type I