Pons Benoit J, Łapińska Urszula, Lopes-Domingues Iolanda, Chisnall Matthew A W, Westra Edze R, Pagliara Stefano, van Houte Stineke
University of Exeter Environment and Sustainability Institute, Penryn TR10 9FE, UK.
Biosciences, University of Exeter Living Systems Institute, Exeter EX4 4QD, UK.
Philos Trans R Soc Lond B Biol Sci. 2025 Sep 4;380(1934):20240474. doi: 10.1098/rstb.2024.0474.
Bacteria evolve resistance against their phage foes with a wide range of resistance strategies whose costs and benefits depend on the level of protection they confer and on the costs for maintainance. can evolve resistance against its phage DMS either by surface mutations that prevent phage binding or through CRISPR-Cas immunity. CRISPR immunity carries an inducible cost whose exact origin is still unknown, and previous work suggested it stems from the inability of the CRISPR-Cas system to completely prevent phage DNA injection and subsequent gene expression before clearing the phage infection. However, the bacterial processes involved are still unknown, and we hypothesize that CRISPR-immunity-associated costs could come from increased mortality rate or reduced growth ability compared with surface-resistant bacteria. To tease apart these two mechanisms with divergent ecological consequences, we use a novel microfluidics-based single-cell approach combined with flow cytometry methods to monitor the effects of phage exposure on the survival and growth of its host. We observed that while CRISPR immunity protects from phage-induced lysis, it cannot prevent phage-induced division lag, filamentation and SOS response activation in a subpopulation of the host bacteria. These results suggest that the costs associated with CRISPR immunity at the population level are caused by heterogeneity in phage-induced growth defects.This article is part of the discussion meeting issue 'The ecology and evolution of bacterial immune systems'.
细菌通过多种抗性策略来进化出对噬菌体敌人的抗性，这些策略的成本和收益取决于它们所提供的保护水平以及维持成本。细菌可以通过阻止噬菌体结合的表面突变或通过CRISPR-Cas免疫来进化出对其噬菌体DMS的抗性。CRISPR免疫带有一种可诱导的成本，其确切来源仍然未知，先前的研究表明它源于CRISPR-Cas系统在清除噬菌体感染之前无法完全阻止噬菌体DNA注射和随后的基因表达。然而，所涉及的细菌过程仍然未知，我们假设与CRISPR免疫相关的成本可能来自与表面抗性细菌相比增加的死亡率或降低的生长能力。为了区分这两种具有不同生态后果的机制，我们使用一种基于微流控的新型单细胞方法结合流式细胞术方法来监测噬菌体暴露对其宿主存活和生长的影响。我们观察到，虽然CRISPR免疫可保护宿主免受噬菌体诱导的裂解，但它无法防止噬菌体诱导的宿主细菌亚群中的分裂延迟、丝状体形成和SOS反应激活。这些结果表明，群体水平上与CRISPR免疫相关的成本是由噬菌体诱导的生长缺陷的异质性引起的。本文是讨论会议议题“细菌免疫系统的生态学和进化”的一部分。
