ECOBIO, Université Rennes 1, 35042, Rennes, France.
School of Microbiology, University College Cork, Cork, T12 YT57, Ireland.
Sci Rep. 2022 Jun 10;12(1):9576. doi: 10.1038/s41598-022-13668-2.
The human gut microbiome, of which the genus Bifidobacterium is a prevalent and abundant member, is thought to sustain and enhance human health. Several surface-exposed structures, including so-called sortase-dependent pili, represent important bifidobacterial gut colonization factors. Here we show that expression of two sortase-dependent pilus clusters of the prototype Bifidobacterium breve UCC2003 depends on replication slippage at an intragenic G-tract, equivalents of which are present in various members of the Bifidobacterium genus. The nature and extent of this slippage is modulated by the host environment. Involvement of such sortase-dependent pilus clusters in microbe-host interactions, including bacterial attachment to the gut epithelial cells, has been shown previously and is corroborated here for one case. Using a Maximum Depth Sequencing strategy aimed at excluding PCR and sequencing errors introduced by DNA polymerase reagents, specific G-tract sequences in B. breve UCC2003 reveal a range of G-tract lengths whose plasticity within the population is functionally utilized. Interestingly, replication slippage is shown to be modulated under in vivo conditions in a murine model. This in vivo modulation causes an enrichment of a G-tract length which appears to allow biosynthesis of these sortase-dependent pili. This work provides the first example of productive replication slippage influenced by in vivo conditions. It highlights the potential for microdiversity generation in "beneficial" gut commensals.
人类肠道微生物群，其中双歧杆菌属是一个普遍存在且丰富的成员，被认为维持和增强人类健康。几种表面暴露的结构，包括所谓的依赖于分选酶的菌毛，是双歧杆菌肠道定植因子的重要代表。在这里，我们展示了原型双歧杆菌短双歧杆菌 UCC2003 的两个依赖于分选酶的菌毛簇的表达依赖于基因内 G-链的复制滑动，双歧杆菌属的各种成员都存在这种 G-链。这种滑动的性质和程度受到宿主环境的调节。先前已经证明了这种依赖于分选酶的菌毛簇在微生物-宿主相互作用中的参与，包括细菌与肠道上皮细胞的附着，这里也证实了一种情况。使用旨在排除聚合酶试剂引入的 PCR 和测序错误的最大深度测序策略，双歧杆菌短双歧杆菌 UCC2003 中的特定 G-链序列揭示了一系列 G-链长度，其在种群中的可塑性被功能利用。有趣的是，复制滑动在体内条件下在小鼠模型中被证明是可调节的。这种体内调节导致了 G-链长度的富集，这似乎允许这些依赖于分选酶的菌毛的生物合成。这项工作提供了第一个受体内条件影响的有生产力的复制滑动的例子。它突出了“有益”肠道共生菌中微多样性产生的潜力。
