A Primed Subpopulation of Bacteria Enables Rapid Expression of the Type 3 Secretion System in Pseudomonas aeruginosa.
A Primed Subpopulation of Bacteria Enables Rapid Expression of the Type 3 Secretion System in Pseudomonas aeruginosa.
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DOI：
10.1128/mbio.00831-21
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发表时间：
2021-06-29
期刊：
影响因子：
6.4
通讯作者：
Kazmierczak B
中科院分区：
文献类型：
--
作者：
Lin CK;Lee DSW;McKeithen-Mead S;Emonet T;Kazmierczak B
3型分泌系统（T3SS）是复杂的纳米机器，跨越细胞包膜，在革兰氏阴性病原体和共生体的生物学中发挥核心作用。在铜绿假单胞菌中，T3SS表达与人类疾病严重程度和小鼠急性肺炎模型中的死亡率密切相关。等基因细胞均匀暴露于T3SS激活信号导致这一关键毒力性状的异质表达。为了了解这种多样性的功能，我们测量了生产的T3SS主调节ExsA和T3SS基因的表达，使用荧光报告。我们发现，ExsA的异质性表达在激活信号的情况下产生一个“引发”的细胞亚群，可以快速诱导T3SS基因表达的信号响应。T3SS表达伴随着生殖权衡，如通过T3SS表达细胞的分裂时间增加所测量的。尽管T3SS引发的细胞是群体中的少数，但它们在活化后的几个小时内构成了大多数T3SS表达细胞。因此，致敏状态允许铜绿假单胞菌最大化繁殖适应性，同时保持快速表达T3SS的能力。由于T3 SS效应器可以作为非生产细胞的共享公共产品，因此这种分工使整个人群受益。
Type 3 secretion systems (T3SS) are complex nanomachines that span the cell envelope and play a central role in the biology of Gram-negative pathogens and symbionts. In Pseudomonas aeruginosa, T3SS expression is strongly associated with human disease severity and with mortality in murine acute pneumonia models. Uniform exposure of isogenic cells to T3SS-activating signal results in heterogeneous expression of this critical virulence trait. To understand the function of such diversity, we measured the production of the T3SS master regulator ExsA and the expression of T3SS genes using fluorescent reporters. We found that heterogeneous expression of ExsA in the absence of activating signal generates a “primed” subpopulation of cells that can rapidly induce T3SS gene expression in response to signal. T3SS expression is accompanied by a reproductive trade-off as measured by increased division time of T3SS-expressing cells. Although T3SS-primed cells are a minority of the population, they compose the majority of T3SS-expressing cells for several hours following activation. The primed state therefore allows P. aeruginosa to maximize reproductive fitness while maintaining the capacity to quickly express the T3SS. As T3SS effectors can serve as shared public goods for nonproducing cells, this division of labor benefits the population as a whole.