Arginine Metabolism Powers Salmonella Resistance to Oxidative Stress.
Arginine Metabolism Powers Salmonella Resistance to Oxidative Stress.
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精氨酸代谢增强沙门氏菌对氧化应激的抵抗力。
DOI：
10.1128/iai.00120-23
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发表时间：
2023
影响因子：
3.1
通讯作者：
Vázquez-Torres,Andrés
中科院分区：
文献类型：
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作者：
Margolis,Alyssa;Liu,Lin;Porwollik,Steffen;Till,JamesKarlA;Chu,Weiping;McClelland,Michael;Vázquez-Torres,Andrés
沙门氏菌侵入宿主细胞，并在酸化、重塑的空泡内复制，这些空泡暴露于先天免疫反应产生的活性氧（ROS）。吞噬细胞NADPH氧化酶的氧化产物部分通过破坏细胞内沙门氏菌的ΔpH来介导抗微生物活性。鉴于精氨酸在细菌对酸性pH的耐受性中的作用，我们筛选了沙门氏菌中54个单基因突变体的文库，这些突变体各自参与但不完全阻断精氨酸代谢。我们确定了几个突变体，影响沙门氏菌在小鼠中的毒力。精氨酸生物合成缺陷的三重突变体ΔargCBH在免疫活性小鼠中减弱，但在吞噬细胞NADPH氧化酶缺陷的Cybb −/−小鼠中恢复毒力。此外，Δ argCBH沙门氏菌对过氧化氢的抑菌和杀菌作用非常敏感。过氧化氢胁迫导致Δ argCBH突变体中ΔpH比野生型沙门氏菌更大的崩溃。外源性精氨酸的加入使Δ argCBH沙门氏菌免于过氧化物诱导的ΔpH崩溃和杀死。结合，这些观察结果表明，精氨酸代谢是一个迄今为止未知的毒力决定因素，有助于沙门氏菌的抗氧化防御，通过保持pH值的稳态。在吞噬细胞NADPH氧化酶产生的ROS的情况下，宿主细胞衍生的dl-精氨酸似乎满足细胞内沙门氏菌的需要。然而，在氧化应激下，沙门氏菌必须额外依赖新生生物合成来维持完整的毒力。
Salmonella invades host cells and replicates inside acidified, remodeled vacuoles that are exposed to reactive oxygen species (ROS) generated by the innate immune response. Oxidative products of the phagocyte NADPH oxidase mediate antimicrobial activity, in part, by collapsing the ΔpH of intracellular Salmonella. Given the role of arginine in bacterial resistance to acidic pH, we screened a library of 54 single-gene mutants in Salmonella that are each involved in, but do not entirely block, arginine metabolism. We identified several mutants that affected Salmonella virulence in mice. The triple mutant ΔargCBH, which is deficient in arginine biosynthesis, was attenuated in immunocompetent mice, but recovered virulence in phagocyte NADPH oxidase deficientCybb−/−mice. Furthermore, ΔargCBHSalmonella was profoundly susceptible to the bacteriostatic and bactericidal effects of hydrogen peroxide. Peroxide stress led to a larger collapse of the ΔpH in ΔargCBHmutants than occurred in wild-type Salmonella. The addition of exogenous arginine rescued ΔargCBHSalmonella from peroxide-induced ΔpH collapse and killing. Combined, these observations suggest that arginine metabolism is a hitherto unknown determinant of virulence that contributes to the antioxidant defenses of Salmonella by preserving pH homeostasis. In the absence of phagocyte NADPH oxidase-produced ROS, host cell-derivedl-arginine appears to satisfy the needs of intracellular Salmonella. However, under oxidative stress, Salmonella must additionally rely onde novobiosynthesis to maintain full virulence.