The extracellular proteome of two Bifidobacterium species reveals different adaptation strategies to low iron conditions
The extracellular proteome of two Bifidobacterium species reveals different adaptation strategies to low iron conditions
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两种双歧杆菌的细胞外蛋白质组揭示了对低铁条件的不同适应策略
作者：
Pamela Vazquez;M. Stevens;P. Gehrig;Simon Barkow;C. Lacroix;C. Chassard
背景双歧杆菌是最早在肠道定植的厌氧菌之一。双歧杆菌生长需要铁，它们的铁螯合机制对它们的适应性很重要，并可能抑制肠道病原体。在这里，我们使用基因组和蛋白质组学分析相结合的特点适应低铁条件的B。kashiwanohense PV 20 -2和B. pseudolongum PV 8 -2，2菌株分离自铁缺乏的非洲婴儿的粪便，并选择其高铁螯合能力。一个铁和亚铁操纵子编码的结合蛋白和转运蛋白被发现在这两个菌株。值得注意的是，B的三价铁操纵子。在其它B中未发现pseudolongum PV 8 -2。假长杆菌菌株，并且可能通过水平基因转移获得。基因组B。此外，我们还利用基因组-蛋白质组学方法对两株菌在低铁条件下生长的分泌物进行了分析。在B的分泌组中发现了三价铁转运蛋白。pseudolongum PV 8 -2，而在B的分泌组中检测到亚铁结合蛋白。kashiwanohense PV 20 -2，表明在菌株中摄取铁的不同策略。此外，蛋白质，如延伸因子，甘油醛-3-磷酸脱氢酶，和应激蛋白GroEL和DnaK被确定在两个分泌。这些蛋白质与乳酸杆菌对上皮细胞的粘附有关。结论B的基因组和分泌组分析。kashiwanohense PV 20 -2和B. pseudolongum PV 8 -2揭示了对低铁条件的不同适应，并鉴定了用于铁转运的胞外蛋白。所鉴定的胞外蛋白可能参与胃肠道中对铁的竞争。
BackgroundBifidobacteria are among the first anaerobic bacteria colonizing the gut. Bifidobacteria require iron for growth and their iron-sequestration mechanisms are important for their fitness and possibly inhibit enteropathogens. Here we used combined genomic and proteomic analyses to characterize adaptations to low iron conditions of B. kashiwanohense PV20-2 and B. pseudolongum PV8-2, 2 strains isolated from the feces of iron-deficient African infants and selected for their high iron-sequestering ability.ResultsAnalyses of the genome contents revealed evolutionary adaptation to low iron conditions. A ferric and a ferrous iron operon encoding binding proteins and transporters were found in both strains. Remarkably, the ferric iron operon of B. pseudolongum PV8-2 is not found in other B. pseudolongum strains and likely acquired via horizontal gene transfer. The genome B. kashiwanohense PV20-2 harbors a unique region encoding genes putatively involved in siderophore production.Additionally, the secretomes of the two strains grown under low-iron conditions were analyzed using a combined genomic-proteomic approach. A ferric iron transporter was found in the secretome of B. pseudolongum PV8-2, while ferrous binding proteins were detected in the secretome of B. kashiwanohense PV20-2, suggesting different strategies to take up iron in the strains. In addition, proteins such as elongation factors, a glyceraldehyde-3-phosphate dehydrogenase, and the stress proteins GroEL and DnaK were identified in both secretomes. These proteins have been previously associated with adhesion of lactobacilli to epithelial cells.ConclusionAnalyses of the genome and secretome of B. kashiwanohense PV20-2 and B. pseudolongum PV8-2 revealed different adaptations to low iron conditions and identified extracellular proteins for iron transport. The identified extracellular proteins might be involved in competition for iron in the gastrointestinal tract.
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