喜温嗜酸硫杆菌SM-1的ROS防护机制

Defense mechanisms of Acidithiobacillus caldus SM-1 responding to reactive oxygen species

摘要:

【目的】从基因组水平探讨生物冶金微生物——喜温嗜酸硫杆菌(Acidithiobacillus caldus)的活性氧类物质(Reactive oxygen species，ROS)防护机制。【方法】采用罗氏454 GS FLX测序平台对喜温嗜酸硫杆菌SM-1进行全基因组测序，利用NCBI非冗余蛋白数据库、Uniport蛋白数据库对全基因组序列进行功能注释，并采用基因组百科全书数据库(KEGG)进行基因组代谢途径重构，通过比较基因组学方法分析SM-1基因组中参与ROS防护相关的基因及可能的分子机制。【结果】SM-1细胞内的酶促抗氧化系统可用于清除细胞内产生的ROS物质，而非酶促抗氧化系统可用于维持细胞内的还原性内环境；细胞内的DNA损伤修复系统可用于修复DNA的氧化损伤从而保持个体遗传物质的稳定性。此外，SM-1基因组中大量的转座元件可能会增加基因组的可塑性以适应极端冶金环境。【结论】SM-1基因组序列的获得为从整体水平揭示喜温嗜酸硫杆菌适应生物冶金环境ROS氧化损伤的防护机制提供了帮助，对于SM-1的ROS防护机制的认知也为进一步通过遗传改造、提升其在高浓度重金属离子冶金环境中的抗性、提高冶金效率提供了理论指导。

Abstract:

[Objective] To discover the defense mechanisms of Acidithiobacillus caldus SM-1 responding to reactive oxygen species at the whole genome level. [Methods] The genomic DNA of At. caldus SM-1 was sequenced by the Roche 454 Genome Sequencer FLX instrument. Gene function was annotated by homology searching in the NCBI NR (non-redundant) and UniProt protein database. The KEGG database was used to reconstruct the metabolism pathways in the cell. Genes related to ROS defense mechanisms were identified through the comparative genomic analysis. [Results] Enzymatic and non-enzymatic antioxidant systems were both identified in the SM-1 genome. The former was used to eliminate the ROS and the latter was utilized to provide a reducing intracellular environment through maintaining the redox homeostasis in the cell. The robust DNA repair system was used to deal with DNA oxidative damage. In addition, whether the large number of transposable elements in the SM-1 genome might enhance the genome plasticity for adaptation to extreme bioleaching environments is still need further interpretation. [Conclusion] Genome sequence of SM-1 will help us to discover the ROS detoxification mechanisms of SM-1, and this will give us insights to construct the engineered stains with better bioleaching performance.