Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
Appl Environ Microbiol. 2019 Jan 9;85(2). doi: 10.1128/AEM.02297-18. Print 2019 Jan 15.
is found in the oral cavity and nasopharynx and forms a significant portion of the human microbiome. In this study, analyses indicated the presence of an Rgg regulator and short hydrophobic peptide (Rgg/SHP) cell-to-cell communication system in Although Rgg presented greater similarity to a repressor in , autoinducing assays and genetic mutation analysis revealed that in Rgg acts as an activator. Transcriptome analysis showed that in addition to , the system regulates two other downstream genes, comprising a segment of a putative lantibiotic gene cluster that is in a conjugative element locus in different members of the mitis group. Close comparison to a similar lantibiotic gene cluster in indicated that lacked the full set of genes. Despite the potential of SHP to trigger a futile cycle of autoinduction, growth was not significantly affected for the mutant under normal or antibiotic stress conditions. The SHP was, however, fully functional in promoting cross-species communication and increasing surface polysaccharide production, which in this species is regulated by Rgg/SHP. The activity of SHPs produced by both species was detected in cocultures using a reporter strain. In competitive assays, a slight advantage was observed for the mutants. We conclude that the Rgg/SHP system in regulates the expression of its own and activates an Rgg/SHP system in that regulates surface polysaccharide synthesis. Fundamentally, cross-communication of such systems may have a role during multispecies interactions. Bacteria secrete signal molecules into the environment which are sensed by other cells when the density reaches a certain threshold. In this study, we describe a communication system in , a commensal species from the oral cavity, which we also found in several species and strains of streptococci from the mitis group. Further, we show that this system can promote cross-communication with , a closely related major human pathogen. Importantly, we show that this cross-communication can take place during coculture. While the genes regulated in are likely part of a futile cycle of activation, the target genes in are potentially involved in virulence. The understanding of such complex communication networks can provide important insights into the dynamics of bacterial communities.
存在于口腔和鼻咽部，构成了人类微生物组的重要组成部分。在这项研究中，分析表明，在 中存在一个 Rgg 调节子和短疏水性肽 (Rgg/SHP) 细胞间通讯系统。尽管 Rgg 与 中的阻遏物更相似，但自动诱导测定和遗传突变分析表明，在 中，Rgg 作为激活剂发挥作用。转录组分析表明，除了 之外，该系统还调节另外两个下游基因，包括假定的类细菌素基因簇的一个片段，该基因簇位于米氏链球菌不同成员的可移动元件基因座中。与 中的类似类细菌素基因簇的密切比较表明， 缺乏全套基因。尽管 SHP 有可能引发无效的自动诱导循环，但在正常或抗生素应激条件下， 突变体的生长并没有受到显著影响。然而， SHP 在促进种间通讯和增加 表面多糖产生方面完全发挥作用，在该物种中，Rgg/SHP 调节表面多糖产生。使用 报告菌株在共培养物中检测到两种物种产生的 SHPs 的活性。在竞争测定中，观察到 突变体略有优势。我们得出结论， 中的 Rgg/SHP 系统调节自身的表达，并激活 中的 Rgg/SHP 系统，该系统调节表面多糖合成。从根本上讲，这种系统的交叉通讯可能在多物种相互作用中发挥作用。细菌将信号分子分泌到环境中，当密度达到一定阈值时，其他细胞就会感知到这些信号分子。在这项研究中，我们描述了一种通讯系统，它存在于口腔共生物种 中，我们也在米氏链球菌的几个物种和菌株中发现了这种系统。此外，我们表明，该系统可以促进与 之间的交叉通讯， 是一种密切相关的主要人类病原体。重要的是，我们表明这种交叉通讯可以在共培养物中进行。虽然在 中调节的基因可能是激活的无效循环的一部分，但 中的靶基因可能与毒力有关。对这种复杂通讯网络的理解可以为细菌群落的动态提供重要的见解。
