Coker James A, DasSarma Priya, Kumar Jeffrey, Müller Jochen A, DasSarma Shiladitya
University of Maryland Biotechnology Institute, Center of Marine Biotechnology, Baltimore, MD 21202, USA.
Saline Syst. 2007 Jul 25;3:6. doi: 10.1186/1746-1448-3-6.
The model halophile Halobacterium sp. NRC-1 was among the first Archaea to be completely sequenced and many post-genomic tools, including whole genome DNA microarrays are now being applied to its analysis. This extremophile displays tolerance to multiple stresses, including high salinity, extreme (non-mesophilic) temperatures, lack of oxygen, and ultraviolet and ionizing radiation.
In order to study the response of Halobacterium sp. NRC-1 to two common stressors, salinity and temperature, we used whole genome DNA microarrays to assay for changes in gene expression under differential growth conditions. Cultures grown aerobically in rich medium at 42 degrees C were compared to cultures grown at elevated or reduced temperature and high or low salinity. The results obtained were analyzed using a custom database and microarray analysis tools. Growth under salt stress conditions resulted in the modulation of genes coding for many ion transporters, including potassium, phosphate, and iron transporters, as well as some peptide transporters and stress proteins. Growth at cold temperature altered the expression of genes involved in lipid metabolism, buoyant gas vesicles, and cold shock proteins. Heat shock showed induction of several known chaperone genes. The results showed that Halobacterium sp. NRC-1 cells are highly responsive to environmental changes at the level of gene expression.
Transcriptional profiling showed that Halobacterium sp. NRC-1 is highly responsive to its environment and provided insights into some of the specific responses at the level of gene expression. Responses to changes in salt conditions appear to be designed to minimize the loss of essential ionic species and abate possible toxic effects of others, while exposure to temperature extremes elicit responses to promote protein folding and limit factors responsible for growth inhibition. This work lays the foundation for further bioinformatic and genetic studies which will lead to a more comprehensive understanding of the biology of a model halophilic Archaeon.
嗜盐菌盐生盐杆菌NRC-1是最早完成全基因组测序的古菌之一，现在许多后基因组工具，包括全基因组DNA微阵列，正被应用于对其进行分析。这种极端微生物对多种胁迫具有耐受性，包括高盐度、极端（非嗜温）温度、缺氧以及紫外线和电离辐射。
为了研究盐生盐杆菌NRC-1对两种常见胁迫因素——盐度和温度的反应，我们使用全基因组DNA微阵列来检测在不同生长条件下基因表达的变化。将在富含营养的培养基中于42℃需氧培养的菌液与在升高或降低的温度以及高盐或低盐条件下培养的菌液进行比较。使用定制数据库和微阵列分析工具对所得结果进行分析。在盐胁迫条件下生长导致许多离子转运蛋白编码基因的调控，包括钾、磷酸盐和铁转运蛋白，以及一些肽转运蛋白和应激蛋白。在低温下生长改变了参与脂质代谢、浮力气体囊泡和冷休克蛋白相关基因的表达。热休克显示出几个已知伴侣基因的诱导。结果表明，盐生盐杆菌NRC-1细胞在基因表达水平上对环境变化高度敏感。
转录谱分析表明，盐生盐杆菌NRC-1对其环境高度敏感，并在基因表达水平上为一些特定反应提供了见解。对盐条件变化的反应似乎旨在尽量减少必需离子种类的损失并减轻其他离子可能的毒性作用，而暴露于极端温度下则引发促进蛋白质折叠和限制生长抑制因素的反应。这项工作为进一步的生物信息学和遗传学研究奠定了基础，这将有助于更全面地了解嗜盐古菌模型的生物学特性。
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