Extracellular Vesicles Produced by Bifidobacterium longum Export Mucin-Binding Proteins
Extracellular Vesicles Produced by Bifidobacterium longum Export Mucin-Binding Proteins
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DOI：
10.1128/aem.01464-20
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发表时间：
2020-10-01
影响因子：
4.4
通讯作者：
Okada, Nobuhiko
中科院分区：
文献类型：
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作者：
Nishiyama, Keita;Takaki, Takashi;Okada, Nobuhiko
细胞外蛋白是宿主与微生物相互作用的重要因子；然而，使双歧杆菌在胃肠道（GI）中粘附和存活的具体因素尚未完全表征。在这里，我们发现在人类粪便发酵液的无细菌上清液中培养的长双歧杆菌NCC2705向细胞外环境释放了无数颗粒。本研究的目的是表征这些细胞外颗粒的生理特性。颗粒直径约为50 ~ 80 nm，具有较高的蛋白质和双链DNA含量，表明它们是细胞外囊泡（EVs）。蛋白质组学分析表明，EVs主要由细胞质蛋白组成，在基本细胞过程中具有重要功能。我们通过对磷酸酮醇酶、GroEL、延伸因子Tu （EF-Tu）、磷酸甘油酸激酶、转醛缩酶（Tal）和热休克蛋白20 （Hsp20）进行生物分子相互作用分析，确定了几种黏液结合蛋白。重组蛋白GroEL和Tal与粘蛋白具有较高的结合亲和力。此外，这些蛋白在微球上的固定化影响了微球在小鼠胃肠道中的持久性。这些结果表明，模拟肠道的双歧杆菌暴露条件刺激长芽胞杆菌的EV产生。由此产生的ev输出了几种可能促进B. Iongum粘附的细胞质蛋白。这项研究提高了我们对肠道微生物群中双歧杆菌定植策略的理解。双歧杆菌是人类胃肠道（GI）的天然居民。形态学观察表明，在复杂的微生物群落中，双歧杆菌的细胞外附属物对于理解其对胃肠道环境的适应非常重要。我们发现长双歧杆菌在无细菌的粪便发酵液中产生动态的细胞外囊泡（EV），这强烈暗示了胃肠道中不同的双歧杆菌细胞外附属物。此外，由ev介导的粘附性兼职蛋白的输出可能促进双歧杆菌的定植。这项研究为研究EVs在双歧杆菌定植过程中的作用提供了新的视角，因为这些细菌适应了胃肠道环境。
Extracellular proteins are important factors in host-microbe interactions; however, the specific factors that enable bifidobacterial adhesion and survival in the gastrointestinal (GI) tract are not fully characterized. Here, we discovered that Bifidobacterium longum NCC2705 cultured in bacterium-free supernatants of human fecal fermentation broth released a myriad of particles into the extracellular environment. The aim of this study was to characterize the physiological properties of these extracellular particles. The particles, approximately 50 to 80 nm in diameter, had high protein and double-stranded DNA contents, suggesting that they were extracellular vesicles (EVs). A proteomic analysis showed that the EVs primarily consisted of cytoplasmic proteins with crucial functions in essential cellular processes. We identified several mucin-binding proteins by performing a biomolecular interaction analysis of phosphoketolase, GroEL, elongation factor Tu (EF-Tu), phosphoglycerate kinase, transaldolase (Tal), and heat shock protein 20 (Hsp20). The recombinant GroEL and Tal proteins showed high binding affinities to mucin. Furthermore, the immobilization of these proteins on microbeads affected the permanence of the microbeads in the murine GI tract. These results suggest that bifidobacterial exposure conditions that mimic the intestine stimulate B. longum EV production. The resulting EVs exported several cytoplasmic proteins that may have promoted B. Iongum adhesion. This study improved our understanding of the Bifidobacterium colonization strategy in the intestinal microbiome.IMPORTANCE Bifidobacterium is a natural inhabitant of the human gastrointestinal (GI) tract. Morphological observations revealed that extracellular appendages of bifidobacteria in complex microbial communities are important for understanding its adaptations to the GI tract environment. We identified dynamic extracellular vesicle (EV) production by Bifidobacterium longum in bacterium-free fecal fermentation broth that was strongly suggestive of differing bifidobacterial extracellular appendages in the GI tract. In addition, export of the adhesive moonlighting proteins mediated by EVs may promote bifidobacterial colonization. This study provides new insight into the roles of EVs in bifidobacterial colonization processes as these bacteria adapt to the GI environment.