Unraveling the molecular determinants of the anti-phagocytic protein cloak of plague bacteria.
Unraveling the molecular determinants of the anti-phagocytic protein cloak of plague bacteria.
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DOI：
10.1371/journal.ppat.1010447
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发表时间：
2022-03
期刊：
影响因子：
6.7
通讯作者：
中科院分区：
文献类型：
--
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致病细菌鼠疫耶尔森氏菌被一种囊状抗原F1保护，使其不被巨噬细胞吞噬，F1是由单体蛋白CAF1的长聚合物形成的。然而，尽管这种病原体很重要，但其保护机制尚不清楚。在这里，我们演示了F1如何保护细菌不被吞噬。首先，我们证明了表达F1的大肠杆菌对巨噬细胞的粘附性大大降低。此外，少数确实黏附的细胞仍然留在巨噬细胞表面，没有被吞噬。然后，我们通过突变将“RGDS”整合素结合基序插入到CAF1中。这并没有改变黏附在巨噬细胞上的细胞数量，但增加了被吞噬的黏附细胞的比例。因此，F1以两种不同的方式保护细胞，可能通过充当聚合物刷子来减少细胞黏附，以及隐藏吞噬所需的固有受体结合部位。F1是非常健壮的，我们证明了表达弱化突变聚合物的大肠杆菌像RGDS突变体一样被吞噬。这表明，如果F1减弱，天然细胞表面的天然附着部位就会暴露出来。单分子力谱(SMFS)实验表明，野生型F1表现出很高的机械稳定性，为400pN。然而，完全被吞噬的不稳定突变体的机械抵抗力只降低了20%。通过在吞噬过程中仅略微超过施加在CAF1聚合物上的机械力，可能是特殊的拉伸强度演变成抵抗在这一吞噬阶段施加的力。巨噬细胞是一种白细胞，是我们免疫防御的重要组成部分。他们询问其他细胞的表面以寻找分子线索，并在一个被称为吞噬作用的过程中吞噬那些构成威胁的细胞。毫不奇怪，病原菌已经找到了逃避这一命运的方法。鼠疫耶尔森氏菌产生长聚合性F1外壳蛋白，使其能够避免摄入，但其机制尚不清楚。我们发现，为大肠杆菌细胞配备F1涂层通过两种不同的机制保护它们免受吞噬，减少与巨噬细胞表面的接触，并隐藏告诉巨噬细胞他们是目标的信号。F1也是一种非常稳定的蛋白质聚合物，通过单分子力谱我们发现它也具有很高的抗拉力。令人惊讶的是，仅使这一比例降低20%的突变导致附着的细菌被完全摄取，这表明细胞在识别和摄取之前受到很大的力。因此，F1已经进化出三个显著的特性：(I)物理特性；(Ii)用于抑制表面相互作用的水合聚合物刷子；(Ii)化学特性；(Ii)缺乏吞噬所需的分子识别线索；(Iii)机械特性；(Iii)在表面拉伸过程中保持伪装层的强度。
The pathogenic bacterium Yersina pestis is protected from macrophage engulfment by a capsule like antigen, F1, formed of long polymers of the monomer protein, Caf1. However, despite the importance of this pathogen, the mechanism of protection was not understood. Here we demonstrate how F1 protects the bacteria from phagocytosis. First, we show that Escherichia coli expressing F1 showed greatly reduced adherence to macrophages. Furthermore, the few cells that did adhere remained on the macrophage surface and were not engulfed. We then inserted, by mutation, an “RGDS” integrin binding motif into Caf1. This did not change the number of cells adhering to macrophages but increased the fraction of adherent cells that were engulfed. Therefore, F1 protects in two separate ways, reducing cell adhesion, possibly by acting as a polymer brush, and hiding innate receptor binding sites needed for engulfment. F1 is very robust and we show that E. coli expressing weakened mutant polymers are engulfed like the RGDS mutant. This suggests that innate attachment sites on the native cell surface are exposed if F1 is weakened. Single-molecule force spectroscopy (SMFS) experiments revealed that wild-type F1 displays a very high mechanical stability of 400 pN. However, the mechanical resistance of the destabilised mutants, that were fully engulfed, was only 20% weaker. By only marginally exceeding the mechanical force applied to the Caf1 polymer during phagocytosis it may be that the exceptional tensile strength evolved to resist the forces applied at this stage of engulfment. Macrophages, a type of white blood cell, form an important element of our immune defence. They interrogate other cells’ surfaces for molecular clues and ingest those presenting a threat in a process known as phagocytosis. Not surprisingly, pathogenic bacteria have developed ways to evade this fate. The plague bacterium, Yersinia pestis, produces the long polymeric F1 coat protein which enables it to avoid ingestion, but the mechanism was unclear. We show that equipping Escherichia coli cells with an F1 coat protected them from phagocytosis by two separate mechanisms, reducing contact with the macrophage surface and hiding the signals that tell the macrophages they are targets. F1 is also a very stable protein polymer and using single molecule force spectroscopy we showed it also has a very high resistance to pulling forces. Surprisingly, mutations which reduced this by only 20% caused adherent bacteria to be fully ingested, indicating that cells are subject to significant forces prior to recognition and ingestion. Thus, F1 has evolved three notable properties (i) physical; creation of a hydrated polymer brush to inhibit surface interactions, (ii) chemical; absence of molecular recognition clues needed for engulfment and (iii) mechanical; strength that maintains the camouflage layer during surface stretching.
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DOI：
10.1083/jcb.201007056
发表时间：
2010-12-13
期刊：
The Journal of cell biology
影响因子：
--
作者：
Flannagan RS;Harrison RE;Yip CM;Jaqaman K;Grinstein S
通讯作者：
Grinstein S
DOI：
10.1073/pnas.0702449104
发表时间：
2007-07-10
影响因子：
11.1
作者：
Kress, Holger;Stelzer, Ernst H. K.;Rohrbach, Alexander
通讯作者：
Rohrbach, Alexander
DOI：
10.1016/j.msec.2018.07.063
发表时间：
2018-12-01
影响因子：
7.9
作者：
Dura, Gema;Waller, Helen;Fulton, David A.
通讯作者：
Fulton, David A.
影响因子：
5.6
作者：
Di Yu, Xiao;Fooks, Laura J.;Zavialov, Anton V.
通讯作者：
Zavialov, Anton V.
影响因子：
48
作者：
Li, Mamie Z.;Elledge, Stephen J.
通讯作者：
Elledge, Stephen J.