title: Dissection of the functional domains of an archaeal Holliday junction helicase.
abstract: Helicases and nucleases form complexes that play very important roles in DNA repair pathways some of which interact with each other at Holliday junctions. In this study, we present in vitro and in vivo analysis of Hjm and its interaction with Hjc in Sulfolobus. In vitro studies employed Hjm from the hyperthermophilic archaeon Sulfolobus tokodaii (StoHjm) and its truncated derivatives, and characterization of the StoHjm proteins revealed that the N-terminal module (residues 1-431) alone was capable of ATP hydrolysis and DNA binding, while the C-terminal one (residues 415-704) was responsible for regulating the helicase activity. The region involved in StoHjm-StoHjc (Hjc from S. tokodaii) interaction was identified as part of domain II, domain III (Winged Helix motif), and domain IV (residues 366-645) for StoHjm. We present evidence supporting that StoHjc regulates the helicase activity of StoHjm by inducing conformation change of the enzyme. Furthermore, StoHjm is able to prevent the formation of Hjc/HJ high complex, suggesting a regulation mechanism of Hjm to the activity of Hjc. We show that Hjm is essential for cell viability using recently developed genetic system and mutant propagation assay, suggesting that Hjm/Hjc mediated resolution of stalled replication forks is of crucial importance in archaea. A tentative pathway with which Hjm/Hjc interaction could have occurred at stalled replication forks is discussed.
authors: State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nan Rd., Jinan, PR China.
authors: Ye
authors: Y
authors: Hong
authors: Mingzhu
authors: M
authors: Chu
authors: Yansheng
authors: Y
authors: Li
authors: Jinfeng
authors: J
authors: Ni
authors: Duohong
authors: D
authors: Sheng
authors: Guihua
authors: G
authors: Hou
authors: Qunxin
authors: Q
authors: She
authors: Yulong
authors: Y
authors: Shen
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001483:Base Sequence; D002470:Cell Survival; D004265:DNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D045566:DNA, Cruciform / Q000235:genetics / Q000378:metabolism*; D045565:Holliday Junction Resolvases / Q000378:metabolism; D006868:Hydrolysis; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D016944:Sulfolobus / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism
chemical_list: D045566:DNA, Cruciform; D000255:Adenosine Triphosphate; D045565:Holliday Junction Resolvases; D004265:DNA Helicases