Won Harim I, Watson Sean M, Ahn Jong-Sam, Endres Jennifer L, Bayles Kenneth W, Sadykov Marat R
Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
J Bacteriol. 2021 May 1;203(9). doi: 10.1128/JB.00660-20. Epub 2021 Feb 16.
Under conditions of glucose excess, aerobically growing bacteria predominantly direct carbon flux towards acetate fermentation, a phenomenon known as overflow metabolism or the bacterial 'Crabtree effect'. Numerous studies of the major acetate-generating pathway, the Pta-AckA, revealed its important role in bacterial fitness through the control of central metabolism to sustain balanced growth and cellular homeostasis. In this work, we highlight the contribution of the Pta-AckA pathway to fitness of the spore-forming bacterium, We demonstrate that disruption of the Pta-AckA pathway causes a drastic growth reduction in the mutants and alters the metabolic and energy status of the cells. Our results revealed that inactivation of the Pta-AckA pathway increases the glucose consumption rate, affects intracellular ATP, NAD and NADH levels and leads to a metabolic block at the pyruvate and acetyl-CoA nodes. Consequently, accumulation of intracellular acetyl-CoA and pyruvate forces bacteria to direct carbon into the TCA and/or glyoxylate cycles as well as fatty acid and poly(3-hydroxybutyrate) (PHB) biosynthesis pathways. Notably, the presence of phosphate butyryltransferase in partially compensates for the loss of phosphotransacetylase activity. Furthermore, overexpression of the gene not only eliminates the negative impact of the mutation on fitness, but also restores normal growth in the mutant of the non-butyrate-producing bacterium, Taken together, the results of this study demonstrate the importance of the Pta-AckA pathway for fitness by revealing its critical contribution to the maintenance of metabolic homeostasis during aerobic growth under conditions of carbon overflow. , the etiologic agent of anthrax, is a highly pathogenic, spore-forming bacterium that causes acute, life-threatening disease in both humans and livestock. A greater understanding of the metabolic determinants governing fitness of is essential for the development of successful therapeutic and vaccination strategies aimed at lessening the potential impact of this important biodefense pathogen. This study is the first to demonstrate the vital role of the Pta-AckA pathway in preserving energy and metabolic homeostasis in under conditions of carbon overflow, therefore, highlighting this pathway as a potential therapeutic target for drug discovery. Overall, the results of this study provide important insight into understanding the metabolic processes and requirements driving rapid proliferation during vegetative growth.
在葡萄糖过量的条件下，需氧生长的细菌主要将碳通量导向乙酸发酵，这种现象被称为溢流代谢或细菌的“克奈特效应”。对主要的乙酸生成途径Pta - AckA的大量研究表明，它通过控制中心代谢以维持平衡生长和细胞内稳态，在细菌适应性方面发挥着重要作用。在这项工作中，我们强调了Pta - AckA途径对产芽孢细菌适应性的贡献。我们证明，Pta - AckA途径的破坏会导致突变体的生长急剧减少，并改变细胞的代谢和能量状态。我们的结果表明，Pta - AckA途径的失活会提高葡萄糖消耗率，影响细胞内ATP、NAD和NADH水平，并导致丙酮酸和乙酰辅酶A节点处的代谢阻滞。因此，细胞内乙酰辅酶A和丙酮酸的积累迫使细菌将碳导向三羧酸循环和/或乙醛酸循环以及脂肪酸和聚（3 - 羟基丁酸酯）（PHB）生物合成途径。值得注意的是，[细菌名称]中磷酸丁酰转移酶的存在部分补偿了磷酸转乙酰酶活性的丧失。此外，[基因名称]基因的过表达不仅消除了[突变名称]突变对[细菌名称]适应性的负面影响，还恢复了非丁酸产生菌[细菌名称]突变体的正常生长。综上所述，本研究结果通过揭示Pta - AckA途径在碳溢流条件下需氧生长期间对维持代谢稳态的关键贡献，证明了其对[细菌名称]适应性的重要性。[细菌名称]是炭疽的病原体，是一种高度致病的产芽孢细菌，可在人类和牲畜中引起急性、危及生命的疾病。深入了解控制[细菌名称]适应性的代谢决定因素对于制定旨在减轻这种重要生物防御病原体潜在影响的成功治疗和疫苗接种策略至关重要。本研究首次证明了Pta - AckA途径在碳溢流条件下[细菌名称]中维持能量和代谢稳态的关键作用，因此，突出了该途径作为药物发现潜在治疗靶点的地位。总体而言，本研究结果为理解营养生长期间驱动[细菌名称]快速增殖的代谢过程和需求提供了重要见解。
