Naphthenic acids (NAs) are carboxylic acids with the formula (C_nH_2n+ZO₂) and are among the most toxic, persistent constituents of oil sands process-affected waters (OSPW), produced during oil sands extraction. Currently, the proteins and mechanisms involved in NA biodegradation are unknown. Using LC-MS/MS shotgun proteomics, we identified proteins overexpressed during the growth of Pseudomonas fluorescens Pf-5 on a model NA (4′-n-butylphenyl)-4-butanoic acid (n-BPBA) and commercial NA mixture (Acros). By day 11, >95% of n-BPBA was degraded. With Acros, a 17% reduction in intensity occurred with 10–18 carbon compounds of the Z family −2 to −14 (major NA species in this mixture). A total of 554 proteins (n-BPBA) and 631 proteins (Acros) were overexpressed during growth on NAs, including several transporters (e.g., ABC transporters), suggesting a cellular protective response from NA toxicity. Several proteins associated with fatty acid, lipid, and amino acid metabolism were also overexpressed, including acyl-CoA dehydrogenase and acyl-CoA thioesterase II, which catalyze part of the fatty acid beta-oxidation pathway. Indeed, multiple enzymes involved in the fatty acid oxidation pathway were upregulated. Given the presumed structural similarity between alkyl-carboxylic acid side chains and fatty acids, we postulate that P. fluorescens Pf-5 was using existing fatty acid catabolic pathways (among others) during NA degradation.

中文翻译：

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在荧光假单胞菌 Pf-5 中环烷酸的模型和商业混合物生长过程中的差异蛋白表达

环烷酸 (NAs) 是具有化学式 (C _n H _{2n + Z} O ₂ ) 的羧酸，是油砂开采过程中产生的油砂过程影响水 (OSPW) 中毒性最强、持久性最强的成分之一。目前，NA 生物降解所涉及的蛋白质和机制尚不清楚。使用 LC-MS/MS 鸟枪蛋白质组学，我们在模型 NA（4'-正丁基苯基）-4-丁酸（n - BPBA）和商业 NA 混合物（Acros）上鉴定了荧光假单胞菌Pf-5生长过程中过度表达的蛋白质）。到第 11 天，>95% 的n- BPBA 被降解。使用 Acros，10-18 种碳化合物的强度降低了 17%Z族 -2 至 -14（该混合物中的主要 NA 物种）。总共有 554 种蛋白质 ( n- BPBA) 和 631 种蛋白质 (Acros) 在 NA 上的生长过程中过度表达，包括几种转运蛋白（例如 ABC 转运蛋白），表明对 NA 毒性的细胞保护反应。与脂肪酸、脂质和氨基酸代谢相关的几种蛋白质也被过度表达，包括酰基辅酶 A 脱氢酶和酰基辅酶 A 硫酯酶 II，它们催化部分脂肪酸β-氧化途径。事实上，参与脂肪酸氧化途径的多种酶被上调。鉴于假定的烷基羧酸侧链和脂肪酸之间的结构相似性，我们假设P。荧光素 Pf-5 在 NA 降解过程中使用现有的脂肪酸分解代谢途径（除其他外）。