Department of Biology, Wheaton College, Wheaton, IL, USA.
Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
Gene. 2022 Jan 30;809:146048. doi: 10.1016/j.gene.2021.146048. Epub 2021 Oct 29.
Colonization of the squid Euprymna scolopes by the bacterium Vibrio fischeri depends on bacterial biofilm formation, motility, and bioluminescence. Previous work has demonstrated an inhibitory role for the small RNA (sRNA) Qrr1 in quorum-induced bioluminescence of V. fischeri, but the contribution of the corresponding sRNA chaperone, Hfq, was not examined. We thus hypothesized that V. fischeri Hfq similarly functions to inhibit bacterial bioluminescence as well as regulate other key steps of symbiosis, including bacterial biofilm formation and motility. Surprisingly, deletion of hfq increased luminescence of V. fischeri beyond what was observed for the loss of qrr1 sRNA. Epistasis experiments revealed that, while Hfq contributes to the Qrr1-dependent regulation of light production, it also functions independently of Qrr1 and its downstream target, LitR. This Hfq-dependent, Qrr1-independent regulation of bioluminescence is also independent of the major repressor of light production in V. fischeri, ArcA. We further determined that Hfq is required for full motility of V. fischeri in a mechanism that partially depends on the Qrr1/LitR regulators. Finally, Hfq also appears to function in the control of biofilm formation: loss of Hfq delayed the timing and diminished the extent of wrinkled colony development, but did not eliminate the production of SYP-polysaccharide-dependent cohesive colonies. Furthermore, loss of Hfq enhanced production of cellulose and resulted in increased Congo red binding. Together, these findings point to Hfq as an important regulator of multiple phenotypes relevant to symbiosis between V. fischeri and its squid host.
鱿鱼 Euprymna scolopes 被细菌 Vibrio fischeri 定植依赖于细菌生物膜的形成、运动和生物发光。先前的研究表明，小 RNA（sRNA）Qrr1 在 Vibrio fischeri 的群体感应生物发光中起抑制作用，但对应的 sRNA 伴侣 Hfq 的作用尚未被研究。因此，我们假设 Vibrio fischeri Hfq 同样可以抑制细菌生物发光，并调节其他关键共生步骤，包括细菌生物膜的形成和运动。令人惊讶的是，hfq 的缺失增加了 Vibrio fischeri 的发光强度，超过了 qrr1 sRNA 缺失的情况。上位实验表明，虽然 Hfq 有助于 Qrr1 依赖的光产生调节，但它也独立于 Qrr1 和其下游靶标 LitR 起作用。这种 Hfq 依赖、Qrr1 独立的生物发光调节也独立于 Vibrio fischeri 中主要的光产生抑制剂 ArcA。我们进一步确定，Hfq 是 Vibrio fischeri 完全运动所必需的，其机制部分依赖于 Qrr1/LitR 调节剂。最后，Hfq 似乎也在生物膜形成的控制中起作用：hfq 的缺失延迟了皱缩菌落发育的时间和程度，但并没有消除 SYP-多糖依赖性凝聚菌落的产生。此外，hfq 的缺失增强了纤维素的产生，并导致刚果红结合增加。总之，这些发现表明 Hfq 是与 Vibrio fischeri 与其鱿鱼宿主之间共生关系相关的多种表型的重要调节剂。
