Chen Fan, Rydzewski Kerstin, Kutzner Erika, Häuslein Ina, Schunder Eva, Wang Xinzhe, Meighen-Berger Kevin, Grunow Roland, Eisenreich Wolfgang, Heuner Klaus
Department of Chemistry, Chair of Biochemistry, Technische Universität MünchenGarching, Germany.
Working Group "Cellular Interactions of Bacterial Pathogens", ZBS 2, Robert Koch InstituteBerlin, Germany.
Front Cell Infect Microbiol. 2017 Jun 21;7:275. doi: 10.3389/fcimb.2017.00275. eCollection 2017.
is an intracellular pathogen for many animals causing the infectious disease, tularemia. Whereas subsp. is highly pathogenic for humans, is almost avirulent for humans, but virulent for mice. In order to compare metabolic fluxes between these strains, we performed C-labeling experiments with subsp. wild type (beaver isolate), subsp. strain LVS, or strain U112 in complex media containing either [U-C]glucose, [1,2-C]glucose, [U-C]serine, or [U-C]glycerol. GC/MS-based isotopolog profiling of amino acids, polysaccharide-derived glucose, free fructose, amino sugars derived from the cell wall, fatty acids, 3-hydroxybutyrate, lactate, succinate and malate revealed uptake and metabolic usage of all tracers under the experimental conditions with glucose being the major carbon source for all strains under study. The labeling patterns of the subsp. wild type were highly similar to those of the LVS strain, but showed remarkable differences to the labeling profiles of the metabolites from the strain. Glucose was directly used for polysaccharide and cell wall biosynthesis with higher rates in subsp. or metabolized, with higher rates in glycolysis and the non-oxidative pentose phosphate pathway (PPP). Catabolic turnover of glucose gluconeogenesis was also observed. In all strains, Ala was mainly synthesized from pyruvate, although no pathway from pyruvate to Ala is annotated in the genomes of and . Glycerol efficiently served as a gluconeogenetic substrate in , but only less in the subsp. strains. In any of the studied strains, serine did not serve as a major substrate and was not significantly used for gluconeogenesis under the experimental conditions. Rather, it was only utilized, at low rates, in downstream metabolic processes, e.g., acetyl-CoA in the citrate cycle and for fatty acid biosynthesis, especially in the subsp. strains. In summary, the data reflect differential metabolite fluxes in subsp. and suggesting that the different utilization of substrates could be related to host specificity and virulence of .
是许多动物的细胞内病原体，可引发兔热病这种传染病。其中亚种对人类具有高致病性，而对人类几乎无毒力，但对小鼠有毒力。为了比较这些菌株之间的代谢通量，我们用亚种野生型（海狸分离株）、亚种菌株LVS或菌株U112在含有[U-¹³C]葡萄糖、[1,2-¹³C]葡萄糖、[U-¹³C]丝氨酸或[U-¹³C]甘油的复杂培养基中进行了¹³C标记实验。基于气相色谱/质谱的氨基酸、多糖衍生葡萄糖、游离果糖、细胞壁衍生氨基糖、脂肪酸、3-羟基丁酸、乳酸、琥珀酸和苹果酸的同位素轮廓分析表明，在实验条件下所有示踪剂均被摄取和代谢利用，葡萄糖是所有研究菌株的主要碳源。亚种野生型的标记模式与LVS菌株的高度相似，但与菌株代谢物的标记谱有显著差异。葡萄糖直接用于多糖和细胞壁生物合成，在亚种中速率较高，或在糖酵解和非氧化戊糖磷酸途径（PPP）中代谢，速率较高。还观察到葡萄糖的分解代谢周转即糖异生。在所有菌株中，丙氨酸主要由丙酮酸合成，尽管在和的基因组中没有注释从丙酮酸到丙氨酸的途径。甘油在中有效地作为糖异生底物，但在亚种菌株中作用较小。在任何研究的菌株中，丝氨酸都不作为主要底物，在实验条件下也没有显著用于糖异生。相反，它仅以低速率用于下游代谢过程，例如柠檬酸循环中的乙酰辅酶A以及脂肪酸生物合成，特别是在亚种菌株中。总之，数据反映了亚种和中的不同代谢物通量，表明底物的不同利用可能与的宿主特异性和毒力有关。
