Genetic analysis of the Holliday junction resolvases Hje and Hjc in Sulfolobus islandicus
Genetic analysis of the Holliday junction resolvases Hje and Hjc in Sulfolobus islandicus
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DOI：
10.1007/s00792-015-0734-5
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发表时间：
2015-03-01
期刊：
影响因子：
2.9
通讯作者：
Shen, Yulong
中科院分区：
文献类型：
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作者：
Huang, Qihong;Li, Yansheng;Shen, Yulong
研究了冰岛硫化叶菌（Sulfolobus islandicus）中两种Holliday连接分解酶Hje和Hjc的体内功能。我们发现hje或hjc的缺失对正常细胞生长没有影响，而hje和hjc的缺失是致命的。虽然Hjc是所有古细菌中保守的解离酶，但hje缺失而不是hjc缺失使细胞对DNA损伤剂如羟基脲、顺铂和甲磺酸甲酯比野生型（WT）更敏感。有趣的是，Δ hje的敏感性不能通过从质粒异位表达Hje来挽救，Hje过表达减缓了生长，并且出现了具有超过两个基因组当量的大细胞。我们发现Hje在WT细胞中维持在低水平。此外，转录组学微阵列分析显示，许多基因的转录本，包括那些参与DNA复制，修复，转录调控，细胞分裂的Hje过表达菌株的丰度急剧变化。然而，只有有限的基因上调或下调hje缺失株。我们的研究结果共同表明，Hje是参与DNA修复的主要解离酶，其表达必须在细胞中受到严格控制。
The in vivo functions of Hje and Hjc, two Holliday junction resolvases in Sulfolobus islandicus were investigated. We found that deletion of either hje or hjc had no effect on normal cell growth, while deletion of both hje and hjc is lethal. Although Hjc is the conserved resolvase in all archaea, the hje deletion rather than hjc deletion rendered cells more sensitive to DNA-damaging agents such as hydroxyurea, cisplatin, and methyl methanesulfonate than the wild type (WT). Intriguingly, the sensitivity of Delta hje could not be rescued by ectopic expression of Hje from a plasmid and Hje overexpression slowed growth and large cells appeared with more than two genome equivalents. We showed that Hje was maintained at a low level in WT cells. Furthermore, transcriptomic microarray analysis revealed that the abundance of transcripts of many genes including those involved in DNA replication, repair, transcription regulation, and cell division changed drastically in the Hje-overexpressed strain. However, only limited genes were up- or downregulated in the hje deletion strain. Our findings collectively suggest that Hje is the primary resolvase involved in DNA repair and its expression must be tightly controlled in cells.