Marshall Darrell D, Sadykov Marat R, Thomas Vinai C, Bayles Kenneth W, Powers Robert
Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States.
Department of Pathology and Microbiology, University of Nebraska Medical Center , Omaha, Nebraska 68198, United States.
J Proteome Res. 2016 Apr 1;15(4):1205-12. doi: 10.1021/acs.jproteome.5b01089. Epub 2016 Mar 24.
The phosphotransacetylase-acetate kinase (Pta-AckA) pathway is thought to be a vital ATP generating pathway for Staphylococcus aureus. Disruption of the Pta-AckA pathway during overflow metabolism causes significant reduction in growth rate and viability, albeit not due to intracellular ATP depletion. Here, we demonstrate that toxicity associated with inactivation of the Pta-AckA pathway resulted from an altered intracellular redox environment. Growth of the pta and ackA mutants under anaerobic conditions partially restored cell viability. NMR metabolomics analyses and (13)C6-glucose metabolism tracing experiments revealed the activity of multiple pathways that promote redox (NADH/NAD(+)) turnover to be enhanced in the pta and ackA mutants during anaerobic growth. Restoration of redox homeostasis in the pta mutant by overexpressing l- lactate dehydrogenase partially restored its viability under aerobic conditions. Together, our findings suggest that during overflow metabolism, the Pta-AckA pathway plays a critical role in preventing cell viability defects by promoting intracellular redox homeostasis.
磷酸转乙酰酶-乙酸激酶（Pta-AckA）途径被认为是金黄色葡萄球菌产生ATP的重要途径。在溢流代谢过程中，Pta-AckA途径的破坏会导致生长速率和活力显著降低，尽管这并非由于细胞内ATP耗尽所致。在此，我们证明与Pta-AckA途径失活相关的毒性是由细胞内氧化还原环境改变引起的。pta和ackA突变体在厌氧条件下的生长部分恢复了细胞活力。核磁共振代谢组学分析和¹³C₆-葡萄糖代谢追踪实验表明，在厌氧生长过程中，pta和ackA突变体中促进氧化还原（NADH/NAD⁺）周转的多种途径的活性增强。通过过表达L-乳酸脱氢酶恢复pta突变体中的氧化还原稳态，部分恢复了其在有氧条件下的活力。总之，我们的研究结果表明，在溢流代谢过程中，Pta-AckA途径通过促进细胞内氧化还原稳态，在防止细胞活力缺陷方面发挥着关键作用。
