Holliday junction resolving enzymes of archaeal viruses SIRV1 and SIRV2
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- 作者：Birkenbihl ; R.P. ; Neef ; K. ; Prangishvili ; D. ; Kemper ; B.
- 关键词：recombination ; Holliday junction ; resolving enzyme ; endonuclease ; extremely thermophilic archaea ; T4 endo VII ; endonuclease VII from phage T4 ; T7 endo I ; endonuclease I from phage T7 ; Hjc ; Holliday junction cleaving enzyme ; aa ; amino acid residue(s) ; ORF
- 刊名：Journal of Molecular Biology
- 出版年：2001
- 出版时间：June 22, 2001
- 年：2001
- 卷：309
- 期：5
- 页码：1067-1076
- 全文大小：293 K
文摘
In the final stages of genetic recombination, Holliday junction resolving enzymes transform the four-way DNA intermediate into two duplex DNA molecules by introducing pairs of staggered nicks flanking the junction. This fundamental process is apparently common to cells from all three domains of life. Two cellular resolving enzymes from extremely thermophilic representatives of both kingdoms of the domain Archaea, the euryarchaeon Pyrococcus furiosus and the crenarchaeon Sulfolobus solfataricus, have been described recently. Here we report for the first time the isolation, purification and characterization of Holliday junction cleaving enzymes (Hjc) from two archaeal viruses. Both viruses, SIRV1 and SIRV2, infect Sulfolobus islandicus. Their Hjcs both consist of 121 amino acid residues (aa) differing only by 18 aa. Both proteins bind selectively to synthetic Holliday-structure analogues with an apparent dissociation constant of 25 nM. In the presence of Mg2+ the enzymes produce identical cleavage patterns near the junction. While S. islandicus shows optimal growth at about 80°C, the nucleolytic activities of recombinant SIRV2 Hjc was highest between 45°C and 70°C. Based on their specificity for four-way DNA structures the enzymes may play a general role in genetic recombination, DNA repair and the resolution of replicative intermediates.