Phage liquid crystalline droplets form occlusive sheaths that encapsulate and protect infectious rod-shaped bacteria
Phage liquid crystalline droplets form occlusive sheaths that encapsulate and protect infectious rod-shaped bacteria
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DOI：
10.1073/pnas.1917726117
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发表时间：
2020-03-03
影响因子：
11.1
通讯作者：
Bharat, Tanmay A. M.
中科院分区：
文献类型：
--
作者：
Tarafder, Abul K.;von Kugelgen, Andriko;Bharat, Tanmay A. M.
条件致病菌铜绿假单胞菌是人类耐药性感染的主要原因。铜绿假单胞菌通过上调共生丝状丝膜病毒原噬菌体Pf4的表达来逃避细菌生物膜中的抗生素。我们研究了噬菌体介导的抗生素耐受性的机制，利用生化重建结合结构生物学和高分辨率细胞成像。我们解决了电子cryomicroscopy原子结构的Pf4与和没有其线性单链DNA基因组，并研究了Pf4组装成液晶液滴使用光学显微镜和电子cryomotomography。通过生物化学复制抗生素保护所必需的条件，我们发现噬菌体液晶液滴在杆状细菌周围形成相分离的封闭隔室，从而增加细菌存活。即使当无生命的胶体棒被用来模仿杆状细菌，观察到这些隔间的封装，这表明形状和大小的互补性深刻影响的过程。丝状病毒在原核生物中普遍存在，特别是几种革兰氏阴性细菌病原体，包括脑膜炎奈瑟氏球菌、霍乱弧菌和肠道沙门氏菌含有这些原噬菌体。我们建议，生物物理闭塞介导的分泌丝状分子，如Pf4可能是一个一般的战略，细菌在恶劣的环境中生存。
The opportunistic pathogen Pseudomonas aeruginosa is a major cause of antibiotic-tolerant infections in humans. P. aeruginosa evades antibiotics in bacterial biofilms by up-regulating expression of a symbiotic filamentous inoviral prophage, Pf4. We investigated the mechanism of phage-mediated antibiotic tolerance using biochemical reconstitution combined with structural biology and high-resolution cellular imaging. We resolved electron cryomicroscopy atomic structures of Pf4 with and without its linear single-stranded DNA genome, and studied Pf4 assembly into liquid crystalline droplets using optical microscopy and electron cryotomography. By biochemically replicating conditions necessary for antibiotic protection, we found that phage liquid crystalline droplets form phase-separated occlusive compartments around rod-shaped bacteria leading to increased bacterial survival. Encapsulation by these compartments was observed even when inanimate colloidal rods were used to mimic rod-shaped bacteria, suggesting that shape and size complementarity profoundly influences the process. Filamentous inoviruses are pervasive across prokaryotes, and in particular, several Gram-negative bacterial pathogens including Neisseria meningitidis, Vibrio cholerae, and Salmonella enterica harbor these prophages. We propose that biophysical occlusion mediated by secreted filamentous molecules such as Pf4 may be a general strategy of bacterial survival in harsh environments.