IQUIBICEN-CONICET, Buenos Aires, Argentina.
Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, Buenos Aires, Argentina.
PLoS One. 2024 May 2;19(5):e0301252. doi: 10.1371/journal.pone.0301252. eCollection 2024.
Bacteria are exposed to reactive oxygen and nitrogen species that provoke oxidative and nitrosative stress which can lead to macromolecule damage. Coping with stress conditions involves the adjustment of cellular responses, which helps to address metabolic challenges. In this study, we performed a global transcriptomic analysis of the response of Pseudomonas extremaustralis to nitrosative stress, induced by S-nitrosoglutathione (GSNO), a nitric oxide donor, under microaerobic conditions. The analysis revealed the upregulation of genes associated with inositol catabolism; a compound widely distributed in nature whose metabolism in bacteria has aroused interest. The RNAseq data also showed heightened expression of genes involved in essential cellular processes like transcription, translation, amino acid transport and biosynthesis, as well as in stress resistance including iron-dependent superoxide dismutase, alkyl hydroperoxide reductase, thioredoxin, and glutathione S-transferase in response to GSNO. Furthermore, GSNO exposure differentially affected the expression of genes encoding nitrosylation target proteins, encompassing metalloproteins and proteins with free cysteine and /or tyrosine residues. Notably, genes associated with iron metabolism, such as pyoverdine synthesis and iron transporter genes, showed activation in the presence of GSNO, likely as response to enhanced protein turnover. Physiological assays demonstrated that P. extremaustralis can utilize inositol proficiently under both aerobic and microaerobic conditions, achieving growth comparable to glucose-supplemented cultures. Moreover, supplementing the culture medium with inositol enhances the stress tolerance of P. extremaustralis against combined oxidative-nitrosative stress. Concordant with the heightened expression of pyoverdine genes under nitrosative stress, elevated pyoverdine production was observed when myo-inositol was added to the culture medium. These findings highlight the influence of nitrosative stress on proteins susceptible to nitrosylation and iron metabolism. Furthermore, the activation of myo-inositol catabolism emerges as a protective mechanism against nitrosative stress, shedding light on this pathway in bacterial systems, and holding significance in the adaptation to unfavorable conditions.
细菌会暴露于活性氧和氮物种中，这些物质会引发氧化和硝化应激，导致大分子损伤。应对应激条件涉及细胞反应的调节，这有助于解决代谢挑战。在这项研究中，我们对极端南极假单胞菌在微氧条件下，受到一氧化氮供体 S-亚硝基谷胱甘肽（GSNO）诱导的硝化应激的反应进行了全局转录组分析。分析显示与肌醇分解代谢相关的基因上调；肌醇是一种广泛分布于自然界的化合物，其在细菌中的代谢引起了人们的兴趣。RNAseq 数据还显示，与转录、翻译、氨基酸转运和生物合成等基本细胞过程相关的基因以及与铁依赖性超氧化物歧化酶、烷基氢过氧化物还原酶、硫氧还蛋白和谷胱甘肽 S-转移酶等应激抗性相关的基因表达增强，以响应 GSNO。此外，GSNO 暴露对编码硝化反应靶蛋白的基因的表达有差异影响，包括金属蛋白和具有游离半胱氨酸和/或酪氨酸残基的蛋白质。值得注意的是，与铁代谢相关的基因，如吡咯并嘧啶合成和铁转运基因，在 GSNO 存在下表现出激活，可能是对增强的蛋白质周转的反应。生理测定表明，P. extremaustralis 在有氧和微氧条件下都能有效地利用肌醇，达到与葡萄糖补充培养相当的生长速度。此外，在培养基中添加肌醇可增强 P. extremaustralis 对氧化-硝化应激的耐受性。与硝化应激下吡咯并嘧啶基因的高表达一致，当向培养基中添加肌醇时，观察到吡咯并嘧啶产量增加。这些发现强调了硝化应激对易受硝化的蛋白质和铁代谢的影响。此外，肌醇分解代谢的激活作为一种针对硝化应激的保护机制出现，揭示了该途径在细菌系统中的作用，并在适应不利条件方面具有重要意义。
