Staphylococcus lugdunensis is a coagulase-negative Staphylococcus part of the commensal skin flora but emerge as an important opportunistic pathogen. Because iron limitation is a crucial stress during infectious process, we performed phenotypic study and compared proteomic profiles of this species incubated in absence and in presence of the iron chelator 2,2′-dipyridyl (DIP). No modification of cell morphology nor cell wall thickness were observed in presence of DIP. However iron-limitation condition promoted biofilm formation and reduced the ability to cope with oxidative stress (1 mM H2O2). In addition, S. lugdunensis N920143 cultured with DIP was significantly less virulent in the larvae of Galleria mellonella model of infection than that grown under standard conditions. We verified that these phenotypes were due to an iron limitation by complementation experiments with FeSO4. By mass spectrometry after trypsin digestion, we characterized the first iron-limitation stress proteome in S. lugdunensis. Among 1426 proteins identified, 349 polypeptides were differentially expressed. 222 were more and 127 less abundant in S. lugdunensis incubated in iron-limitation condition, and by RT-qPCR, some of the corresponding genes have been shown to be transcriptionally regulated. Our data revealed that proteins involved in iron metabolism and carriers were over-expressed, as well as several ABC transporters and polypeptides linked to cell wall metabolism. Conversely, enzymes playing a role in the oxidative stress response (especially catalase) were repressed. This phenotypic and global proteomic study allowed characterization of the response of S. lugdunensis to iron-limitation. We showed that iron-limitation promoted biofilm formation, but decrease the oxidative stress resistance that may, at least in part, explained the reduced virulence of S. lugdunensis observed under low iron condition.

中文翻译：

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路敦葡萄球菌对铁限制条件反应的表型和蛋白质组学方法

路敦葡萄球菌是共生皮肤菌群中凝固酶阴性葡萄球菌的一部分，但它是一种重要的机会性病原体。因为铁限制是感染过程中的一个关键压力，我们进行了表型研究并比较了在没有和存在铁螯合剂 2,2'-联吡啶 (DIP) 的情况下孵育的该物种的蛋白质组学特征。在 DIP 存在下，没有观察到细胞形态和细胞壁厚度的改变。然而，铁限制条件促进了生物膜的形成并降低了应对氧化应激（1 mM H2O2）的能力。此外，与在标准条件下生长的相比，用 DIP 培养的 S. lugdunensis N920143 在大蜡螟感染模型的幼虫中的毒性显着降低。我们通过与 FeSO4 的互补实验验证了这些表型是由于铁限制所致。通过胰蛋白酶消化后的质谱分析，我们表征了 S. lugdunensis 中的第一个铁限制应激蛋白质组。在鉴定的 1426 种蛋白质中，有 349 种多肽差异表达。在铁限制条件下孵育的 S. lugdunensis 中 222 个较多，127 个较少，并且通过 RT-qPCR，一些相应的基因已被证明受到转录调控。我们的数据显示，参与铁代谢和载体的蛋白质以及几种与细胞壁代谢相关的 ABC 转运蛋白和多肽过度表达。相反，在氧化应激反应中起作用的酶（尤其是过氧化氢酶）被抑制。这项表型和全球蛋白质组学研究允许表征 S. lugdunensis 对铁限制的反应。我们表明铁限制促进了生物膜的形成，但降低了氧化应激的抵抗力，这可能至少部分解释了在低铁条件下观察到的 S. lugdunensis 毒力降低。