title: Knockouts of RecA-like proteins RadC1 and RadC2 have distinct responses to DNA damage agents in Sulfolobus islandicus.
abstract: RecA family recombinases play essential roles in maintaining genome integrity. A group of RecA-like proteins named RadC are present in all archaea, but their in vivo functions remain unclear. In this study, we performed phylogenetic and genetic analysis of two RadC proteins from Sulfolobus islandicus. RadC is closer to the KaiC lineage of cyanobacteria and proteobacteria than to the lineage of the recombinases (RecA, RadA, and Rad51) and the recombinase paralogs (e.g., RadB, Rad55, and Rad51B). Using the recently-established S. islandicus genetic system, we constructed deletion and over-expression strains of radC1 and radC2. Deletion of radC1 rendered the cells more sensitive to DNA damaging agents, methyl methanesulfonate (MMS), hydroxyurea (HU), and ultraviolet (UV) radiation, than the wild type, and a ΔradC1ΔradC2 double deletion strain was more sensitive to cisplatin and MMS than the ΔradC1 single deletion mutant. In addition, ectopic expression of His-tagged RadC1 revealed that RadC1 was co-purified with a putative structure-specific nuclease and ATPase, which is highly conserved in archaea. Our results indicate that both RadC1 and RadC2 are involved in DNA repair. RadC1 may play a general or primary role in DNA repair, while RadC2 plays a role in DNA repair in response to specific DNA damages.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China.
authors.forename: Peng-Juan
authors.initials: PJ
authors.lastname: Liang
authors.forename: Wen-Yuan
authors.initials: WY
authors.lastname: Han
authors.forename: Qi-Hong
authors.initials: QH
authors.lastname: Huang
authors.forename: Yan-Ze
authors.initials: YZ
authors.lastname: Li
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Ni
authors.forename: Qun-Xin
authors.initials: QX
authors.lastname: She
authors.forename: Yu-Long
authors.initials: YL
authors.lastname: Shen
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics*; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D006918:Hydroxyurea / Q000494:pharmacology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D016944:Sulfolobus / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D019843:Archaeal Proteins; D008741:Methyl Methanesulfonate; D006918:Hydroxyurea
keywords: DNA repair; RadA; RadC; RecA-like protein; Sulfolobus