Gomez Miguel, Leung Whinkie, Dantuluri Swathi, Pillai Alexander, Gani Zyan, Hwang Sungmin, McMillan Lana J, Kiljunen Saija, Savilahti Harri, Maupin-Furlow Julie A
Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
Genetics Institute, University of Florida, Gainesville, FL 32611, USA.
Genes (Basel). 2018 Nov 20;9(11):562. doi: 10.3390/genes9110562.
Halophilic archaea thrive in hypersaline conditions associated with desiccation, ultraviolet (UV) irradiation and redox active compounds, and thus are naturally tolerant to a variety of stresses. Here, we identified mutations that promote enhanced tolerance of halophilic archaea to redox-active compounds using as a model organism. The strains were isolated from a library of random transposon mutants for growth on high doses of sodium hypochlorite (NaOCl), an agent that forms hypochlorous acid (HOCl) and other redox acid compounds common to aqueous environments of high concentrations of chloride. The transposon insertion site in each of twenty isolated clones was mapped using the following: (i) inverse nested two-step PCR (INT-PCR) and (ii) semi-random two-step PCR (ST-PCR). Genes that were found to be disrupted in hypertolerant strains were associated with lysine deacetylation, proteasomes, transporters, polyamine biosynthesis, electron transfer, and other cellular processes. Further analysis revealed a Δ (α1) markerless deletion strain that produces only the α2 and β proteins of 20S proteasomes was hypertolerant to hypochlorite stress compared with wild type, which produces α1, α2, and β proteins. The results of this study provide new insights into archaeal tolerance of redox active compounds such as hypochlorite.
嗜盐古菌在与干燥、紫外线（UV）照射和氧化还原活性化合物相关的高盐环境中茁壮成长，因此对多种压力具有天然耐受性。在此，我们以嗜盐古菌为模式生物，鉴定出了能增强其对氧化还原活性化合物耐受性的突变。这些菌株是从一个随机转座子突变体文库中分离出来的，用于在高剂量次氯酸钠（NaOCl）上生长，NaOCl是一种能形成次氯酸（HOCl）和其他在高浓度氯化物水环境中常见的氧化还原酸性化合物的试剂。使用以下方法对20个分离克隆中的每一个的转座子插入位点进行了定位：（i）反向嵌套两步PCR（INT-PCR）和（ii）半随机两步PCR（ST-PCR）。在高耐受性菌株中发现被破坏的基因与赖氨酸去乙酰化、蛋白酶体、转运蛋白、多胺生物合成、电子传递及其他细胞过程相关。进一步分析发现，与产生α1、α2和β蛋白的野生型相比，仅产生20S蛋白酶体的α2和β蛋白的Δ（α1）无标记缺失菌株对次氯酸盐胁迫具有更高的耐受性。本研究结果为古菌对次氯酸盐等氧化还原活性化合物的耐受性提供了新的见解。
