Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843.
Department of Biology, Texas A&M University, College Station, TX 77843.
Proc Natl Acad Sci U S A. 2020 Mar 17;117(11):6114-6120. doi: 10.1073/pnas.1916974117. Epub 2020 Mar 2.
Bacterial chemotaxis to prominent microbiota metabolites such as indole is important in the formation of microbial communities in the gastrointestinal (GI) tract. However, the basis of chemotaxis to indole is poorly understood. Here, we exposed to a range of indole concentrations and measured the dynamic responses of individual flagellar motors to determine the chemotaxis response. Below 1 mM indole, a repellent-only response was observed. At 1 mM indole and higher, a time-dependent inversion from a repellent to an attractant response was observed. The repellent and attractant responses were mediated by the Tsr and Tar chemoreceptors, respectively. Also, the flagellar motor itself mediated a repellent response independent of the receptors. Chemotaxis assays revealed that receptor-mediated adaptation to indole caused a bipartite response-wild-type cells were attracted to regions of high indole concentration if they had previously adapted to indole but were otherwise repelled. We propose that indole spatially segregates cells based on their state of adaptation to repel invaders while recruiting beneficial resident bacteria to growing microbial communities within the GI tract.
细菌对肠道中突出的微生物代谢物(如吲哚)的趋化作用对于微生物群落的形成非常重要。然而,目前对吲哚趋化作用的基础知之甚少。在这里,我们将暴露于一系列吲哚浓度,并测量单个鞭毛马达的动态响应,以确定趋化反应。在 1mM 以下的吲哚浓度下,仅观察到排斥反应。在 1mM 吲哚及更高浓度下,观察到从排斥反应到吸引反应的时间依赖性反转。排斥和吸引反应分别由 Tsr 和 Tar 化学感受器介导。此外,鞭毛马达本身独立于受体介导排斥反应。趋化作用测定表明,对吲哚的受体介导适应性导致二分反应-如果野生型细胞先前适应于吲哚,它们会被吸引到高吲哚浓度的区域,但否则会被排斥。我们提出,吲哚基于其对抑制剂的适应状态将细胞空间隔离,以排斥入侵者,同时招募有益的常驻细菌到胃肠道内生长的微生物群落中。