Arntzen Magnus Øverlie, Karlskås Ingrid Lea, Skaugen Morten, Eijsink Vincent G H, Mathiesen Geir
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Ås, Norway.
PLoS One. 2015 Apr 27;10(4):e0126694. doi: 10.1371/journal.pone.0126694. eCollection 2015.
Enterococcus faecalis is a robust bacterium, which is able to survive in and adapt to hostile environments such as the urinary tract and bladder. In this label-free quantitative proteomic study based on MaxQuant LFQ algorithms, we identified 127 proteins present in the secretome of the clinical vancomycin-resistant isolate E. faecalis V583 and we compared proteins secreted in the initial phase of cultivation in urine with the secretome during cultivation in standard laboratory medium, 2xYT. Of the 54 identified proteins predicted to be secreted, six were exclusively found after cultivation in urine including the virulence factor EfaA ("endocarditis specific antigen") and its homologue EF0577 ("adhesion lipoprotein"). These two proteins are both involved in manganese transport, known to be an important determinant of colonization and infection, and may additionally function as adhesins. Other detected urine-specific proteins are involved in peptide transport (EF0063 and EF3106) and protease inhibition (EF3054). In addition, we found an uncharacterized protein (EF0764), which had not previously been linked to the adaptation of V583 to a urine environment, and which is unique to E. faecalis. Proteins found in both environments included a histone-like protein, EF1550, that was up-regulated during cultivation in urine and that has a homologue in streptococci (HlpA) known to be involved in bacterial adhesion to host cells. Up-regulated secreted proteins included autolysins. These results from secretome analyses are largely compatible with previously published data from transcriptomics studies. All in all, the present data indicate that transport, in particular metal transport, adhesion, cell wall remodelling and the unknown function carried out by the unique EF0764 are important for enterococcal adaptation to the urine environment. These results provide a basis for a more targeted exploration of novel proteins involved in the adaptability and pathogenicity of E. faecalis.
粪肠球菌是一种顽强的细菌，能够在尿道和膀胱等恶劣环境中存活并适应。在这项基于MaxQuant LFQ算法的无标记定量蛋白质组学研究中，我们鉴定出临床耐万古霉素分离株粪肠球菌V583分泌组中的127种蛋白质，并比较了在尿液中培养初期分泌的蛋白质与在标准实验室培养基2xYT中培养时的分泌组。在预测分泌的54种已鉴定蛋白质中，有6种仅在尿液中培养后发现，包括毒力因子EfaA（“心内膜炎特异性抗原”）及其同源物EF0577（“粘附脂蛋白”）。这两种蛋白质都参与锰运输，已知锰运输是定植和感染的重要决定因素，并且可能还起到粘附素的作用。其他检测到的尿液特异性蛋白质参与肽运输（EF0063和EF3106）和蛋白酶抑制（EF3054）。此外，我们发现了一种未表征的蛋白质（EF0764），它以前未与V583对尿液环境的适应相关联，并且是粪肠球菌特有的。在两种环境中都发现的蛋白质包括一种组蛋白样蛋白质EF1550，它在尿液培养期间上调，并且在已知参与细菌与宿主细胞粘附的链球菌中有同源物（HlpA）。上调的分泌蛋白包括自溶素。这些分泌组分析结果与先前发表的转录组学研究数据基本一致。总而言之，目前的数据表明，运输，特别是金属运输、粘附、细胞壁重塑以及独特的EF0764所执行的未知功能对于肠球菌适应尿液环境很重要。这些结果为更有针对性地探索参与粪肠球菌适应性和致病性的新蛋白质提供了基础。
