Neumann-Schaal Meina, Metzendorf Nicole G, Troitzsch Daniel, Nuss Aaron Mischa, Hofmann Julia Danielle, Beckstette Michael, Dersch Petra, Otto Andreas, Sievers Susanne
Department of Bioinformatics and Biochemistry and Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany.
Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, 17489, Greifswald, Germany.
Anaerobe. 2018 Oct;53:94-107. doi: 10.1016/j.anaerobe.2018.05.018. Epub 2018 May 31.
Clostridioides difficile is the major pathogen causing diarrhea following antibiotic treatment. It is considered to be a strictly anaerobic bacterium, however, previous studies have shown a certain and strain-dependent oxygen tolerance. In this study, the model strain C. difficile 630Δerm was shifted to micro-aerobiosis and was found to stay growing to the same extent as anaerobically growing cells with only few changes in the metabolite pattern. However, an extensive change in gene expression was determined by RNA-Seq. The most striking adaptation strategies involve a change in the reductive fermentation pathways of the amino acids proline, glycine and leucine. But also a far-reaching restructuring in the carbohydrate metabolism was detected with changes in the phosphotransferase system (PTS) facilitated uptake of sugars and a repression of enzymes of glycolysis and butyrate fermentation. Furthermore, a temporary induction in the synthesis of cofactor riboflavin was detected possibly due to an increased demand for flavin mononucleotid (FMN) and flavin adenine dinucleotide (FAD) in redox reactions. However, biosynthesis of the cofactors thiamin pyrophosphate and cobalamin were repressed deducing oxidation-prone enzymes and intermediates in these pathways. Micro-aerobically shocked cells were characterized by an increased demand for cysteine and a thiol redox proteomics approach revealed a dramatic increase in the oxidative state of cysteine in more than 800 peptides after 15 min of micro-aerobic shock. This provides not only a catalogue of oxidation-prone cysteine residues in the C. difficile proteome but also puts the amino acid cysteine into a key position in the oxidative stress response. Our study suggests that tolerance of C. difficile towards O is based on a complex and far-reaching adjustment of global gene expression which leads to only a slight change in phenotype.
艰难梭菌是抗生素治疗后引起腹泻的主要病原体。它被认为是一种严格厌氧的细菌，然而，先前的研究表明其存在一定的、菌株依赖性的氧耐受性。在本研究中，将艰难梭菌模型菌株630Δerm转移至微需氧环境，发现其生长程度与厌氧生长的细胞相同，代谢物模式仅有少量变化。然而，通过RNA测序确定了基因表达的广泛变化。最显著的适应策略涉及氨基酸脯氨酸、甘氨酸和亮氨酸的还原发酵途径的改变。同时还检测到碳水化合物代谢的深远重组，磷酸转移酶系统（PTS）的变化促进了糖的摄取，并抑制了糖酵解和丁酸发酵的酶。此外，检测到辅因子核黄素合成的暂时诱导，这可能是由于氧化还原反应中对黄素单核苷酸（FMN）和黄素腺嘌呤二核苷酸（FAD）的需求增加。然而，焦磷酸硫胺素和钴胺素辅因子的生物合成受到抑制，推断这些途径中存在易于氧化的酶和中间体。微需氧休克细胞的特征是对半胱氨酸的需求增加，硫醇氧化还原蛋白质组学方法显示，微需氧休克15分钟后，800多个肽段中的半胱氨酸氧化状态显著增加。这不仅提供了艰难梭菌蛋白质组中易于氧化的半胱氨酸残基目录，还将氨基酸半胱氨酸置于氧化应激反应的关键位置。我们的研究表明，艰难梭菌对氧的耐受性基于全局基因表达的复杂而深远的调节，这仅导致表型的轻微变化。
