PDF(Pubmed)
Abstract：
Extreme acidophilic bacteria like Leptospirillum sp. require an efficient enzyme system to counteract strong oxygen stress conditions in their natural habitat. The genome of Leptospirillum sp. CF-1 encodes the thioredoxin-fold protein TFP2, which exhibits a high structural similarity to the thioredoxin domain of E. coli CnoX. CnoX from Escherichia coli is a chaperedoxin that protects protein substrates from oxidative stress conditions using its holdase function and a subsequent transfer to foldase chaperones for refolding. Recombinantly produced and purified Leptospirillum sp. TFP2 possesses both thioredoxin and chaperone holdase activities in vitro. It can be reduced by thioredoxin reductase (TrxR). The tfp2 gene co-locates with genes for the chaperone foldase GroES/EL on the chromosome. The \"tfp2 cluster\" (ctpA-groES-groEL-hyp-tfp2-recN) was found between 1.9 and 8.8-fold transcriptionally up-regulated in response to 1 mM hydrogen peroxide (H2O2). Leptospirillum sp. tfp2 heterologously expressed in E. coli wild type and cnoX mutant strains lead to an increased tolerance of these E. coli strains to H2O2 and significantly reduced intracellular protein aggregates. Finally, a proteomic analysis of protein aggregates produced in E. coli upon exposition to oxidative stress with 4 mM H2O2, showed that Leptospirillum sp. tfp2 expression caused a significant decrease in the aggregation of 124 proteins belonging to fifteen different metabolic categories. These included several known substrates of DnaK and GroEL/ES. These findings demonstrate that Leptospirillum sp. TFP2 is a chaperedoxin-like protein, acting as a key player in the control of cellular proteostasis under highly oxidative conditions that prevail in extreme acidic environments.
摘要：
极端嗜酸细菌，例如钩端螺旋体。需要有效的酶系统来抵消其自然栖息地中强烈的氧气胁迫条件。钩端螺旋体的基因组。CF-1编码硫氧还蛋白-折叠蛋白TFP2,其表现出与大肠杆菌CnoX的硫氧还蛋白结构域的高度结构相似性。来自大肠杆菌的CnoX是一种chaperedoxin，可使用其保持酶功能保护蛋白质底物免受氧化应激条件的影响，并随后转移到折叠酶伴侣进行重折叠。重组生产和纯化的钩端螺旋体。TFP2在体外同时具有硫氧还蛋白和伴侣保持酶活性。它可以被硫氧还蛋白还原酶(TrxR)还原。tfp2基因与染色体上的伴侣折叠酶GroES/EL的基因共定位。发现“tfp2簇”（ctpA-groES-groEL-hyp-tfp2-recN）在转录上上调1.9至8.8倍，以响应1mM过氧化氢（H2O2）。钩端螺旋体sp.在大肠杆菌野生型和cnoX突变菌株中异源表达的tfp2导致这些大肠杆菌菌株对H2O2的耐受性增加并显著减少细胞内蛋白聚集体。最后,在暴露于4mMH2O2的氧化应激后，大肠杆菌中产生的蛋白质聚集体的蛋白质组学分析显示，钩端螺旋体。tfp2表达导致属于15种不同代谢类别的124种蛋白质的聚集显着减少。这些包括DnaK和GroEL/ES的几种已知底物。这些发现表明钩端螺旋体sp。TFP2是一种chaperedoxin样蛋白，在极端酸性环境中普遍存在的高度氧化条件下，在控制细胞蛋白停滞方面发挥关键作用。
