Li Jihong, Wu Zhihao, Hou Yuting, Zhang Yong-An, Zhou Yang
State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China.
Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China.
Front Microbiol. 2023 Feb 8;13:1099611. doi: 10.3389/fmicb.2022.1099611. eCollection 2022.
, a ubiquitous bacterium in aquatic habitats with broad host ranges, has earned the nickname of a 'Jack-of-all-trades'. However, there is still a limited understanding of the mechanism of how this bacterium fit the competition with other species in dynamic surroundings. The type VI secretion system (T6SS) is macromolecular machinery found in Gram-negative bacteria's cell envelope that is responsible for bacterial killing and/or pathogenicity toward different host cells. In this study, the depression of T6SS under iron-limiting conditions was detected. The ferric uptake regulator (Fur) was then found to act as an activator of T6SS by directly binding to the Fur box region in A promoter in the T6SS gene cluster. The transcription of A was repressed in Δ. Moreover, the inactivation of Fur resulted in considerable defects in the interbacterial competition activity and pathogenicity of and . These findings provide the first direct evidence that Fur positively regulates the expression and functional activity of T6SS in Gram-negative bacteria and will help to understand the fascinating mechanism of competitive advantage for in different ecological niches.
是水生栖息地中一种广泛存在且宿主范围广泛的细菌，赢得了“多面手”的绰号。然而，对于这种细菌在动态环境中如何与其他物种竞争的机制仍了解有限。VI型分泌系统（T6SS）是在革兰氏阴性细菌细胞膜中发现的大分子机器，负责对不同宿主细胞进行细菌杀伤和/或致病性作用。在本研究中，检测到铁限制条件下T6SS的抑制。随后发现铁摄取调节因子（Fur）通过直接结合T6SS基因簇中A启动子的Fur盒区域而作为T6SS的激活剂。在Δ中A的转录受到抑制。此外，Fur的失活导致和的细菌间竞争活性和致病性出现相当大的缺陷。这些发现提供了首个直接证据，表明Fur正向调节革兰氏阴性细菌中T6SS的表达和功能活性，并将有助于理解在不同生态位中的迷人竞争优势机制。
