Strengthening of enterococcal biofilms by Esp.
Strengthening of enterococcal biofilms by Esp.
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DOI：
10.1371/journal.ppat.1010829
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发表时间：
2022-09
期刊：
影响因子：
6.7
通讯作者：
中科院分区：
文献类型：
--
作者：
多重耐药粪肠球菌是医院获得性感染的主要原因。临床上有大量的E.粪肠球菌具有一个编码肠球菌表面蛋白（Esp）的大的致病岛，其被认为促进生物膜的产生和毒力，但这仍然存在争议。为了解决这个问题，我们表征了Esp N-末端区域，即涉及生物膜产生的部分。小角X射线散射表明，N-末端区域具有球形头部，其由两个DEv-Ig结构域组成，如通过X射线晶体学观察到的，随后是延长的尾部。N-末端区域不是生物膜产生所需的，而是显著增强生物膜抵抗机械或降解破坏，大大增加了肠球菌在生物膜内的保留。生物膜强化需要低pH，这导致Esp展开，聚集，并形成淀粉样结构。生物膜强化的pH阈值取决于蛋白质的稳定性。第一个DEv-Ig结构域的截短片段（可能由宿主蛋白酶产生）是最不稳定的，并且足以在pH ≤ 5.0时加强生物膜，而肠球菌表面上的整个N-末端区域和完整的Esp更稳定，需要pH ≤ 4.3。这些结果表明，在加强肠球菌生物膜在酸性非生物或宿主环境中的毒力作用。粪肠球菌是正常微生物组的一部分，但也可能导致严重的医院获得性感染。从医院分离的肠球菌菌株往往具有某些在微生物组菌株中未发现的蛋白质。因此，这些蛋白质可能在感染中很重要。我们试图通过生物化学、生物物理学和微生物学技术来了解这样一种蛋白质的功能。我们发现细菌表面的Esp形成了淀粉样纤维，阻止了生物膜的去除。生物膜是一种细菌群落，它们被包裹在基质中，在体内或导管等惰性物体上形成。它们通过增加对抗生素的耐药性和干扰免疫系统的清除来促进感染。我们观察到，缺乏Esps的生物膜比具有Esps的生物膜更容易被破坏。我们还发现Esps仅在低pH值下起作用（即，酸性条件）。pH值到底有多低取决于Esp是留在细菌表面还是被蛋白酶从表面释放出来，人类肠道蛋白酶可能是释放的原因。总之，我们发现Esp在酸性条件下起作用，并可能通过阻止生物膜的扩散而有助于毒力。
Multidrug-resistant (MDR) Enterococcus faecalis are major causes of hospital-acquired infections. Numerous clinical strains of E. faecalis harbor a large pathogenicity island that encodes enterococcal surface protein (Esp), which is suggested to promote biofilm production and virulence, but this remains controversial. To resolve this issue, we characterized the Esp N-terminal region, the portion implicated in biofilm production. Small angle X-ray scattering indicated that the N-terminal region had a globular head, which consisted of two DEv-Ig domains as visualized by X-ray crystallography, followed by an extended tail. The N-terminal region was not required for biofilm production but instead significantly strengthened biofilms against mechanical or degradative disruption, greatly increasing retention of Enterococcus within biofilms. Biofilm strengthening required low pH, which resulted in Esp unfolding, aggregating, and forming amyloid-like structures. The pH threshold for biofilm strengthening depended on protein stability. A truncated fragment of the first DEv-Ig domain, plausibly generated by a host protease, was the least stable and sufficient to strengthen biofilms at pH ≤ 5.0, while the entire N-terminal region and intact Esp on the enterococcal surface was more stable and required a pH ≤ 4.3. These results suggested a virulence role of Esp in strengthening enterococcal biofilms in acidic abiotic or host environments. The bacterium Enterococcus faecalis is part of the normal microbiome but can also cause serious hospital-acquired infections. Enterococcus strains isolated from hospitals tend to have certain proteins not found in microbiome strains. Such proteins are therefore likely to be important in infection. We sought to understand the function of one such protein, Esp, through biochemical, biophysical, and microbiological techniques. We found that Esp, which is on the bacterial surface, formed amyloid-like fibrils that prevented removal of biofilms. Biofilms are bacterial communities enmeshed within a matrix, and form within the body or on inert objects like catheters. They promote infection by increasing resistance to antibiotics and interfering with clearance by the immune system. We observed that biofilms that lacked Esp could be disrupted much more easily than those that had Esp. We also found that Esp acted only at low pH (i.e., acidic conditions). Exactly how low a pH depended on whether Esp remained on the bacterial surface or was liberated from the surface by a protease, with a human intestinal protease being a likely cause of liberation. In summary, we found that Esp acts at acidic conditions and likely contributes to virulence by preventing the dispersal of biofilms.
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影响因子：
64.5
作者：
Lebreton F;Manson AL;Saavedra JT;Straub TJ;Earl AM;Gilmore MS
通讯作者：
Gilmore MS
影响因子：
3.7
作者：
de Regt MJ;van Schaik W;van Luit-Asbroek M;Dekker HA;van Duijkeren E;Koning CJ;Bonten MJ;Willems RJ
通讯作者：
Willems RJ
影响因子：
3.6
作者：
Brady LJ;Maddocks SE;Larson MR;Forsgren N;Persson K;Deivanayagam CC;Jenkinson HF
通讯作者：
Jenkinson HF
影响因子：
5.7
作者：
Chiba A;Sugimoto S;Sato F;Hori S;Mizunoe Y
通讯作者：
Mizunoe Y
影响因子：
6.4
作者：
Barnes, Aaron M. T.;Ballering, Katie S.;Dunny, Gary M.
通讯作者：
Dunny, Gary M.