Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
Appl Microbiol Biotechnol. 2018 Aug;102(16):7083-7095. doi: 10.1007/s00253-018-9116-0. Epub 2018 Jun 3.
The type VI secretion system (T6SS) has been considered as a crucial factor in bacterial competition and virulence. The hemolysin co-regulated protein (Hcp) is the hallmark of T6SS. The secretion of Hcp in Aeromonas hydrophila Chinese epidemic strain NJ-35 indicated a functional T6SS. In this study, three copies of the hcp gene were identified in the genome of strain NJ-35. We targeted these Hcp family proteins for generating deletion mutants. These mutants showed varying levels in Hcp production, the interaction with other bacteria or eukaryotic cells, and bacterial virulence. Hcp1 was necessary for T6SS assembly and played a predominant role in the bacterial competition; Hcp2 negatively functioned in the biofilm formation and bacterial adhesion and was more involved in the A. hydrophila virulence in zebrafish and survival against the predation of Tetrahymena, and Hcp3 positively influenced the biofilm formation and bacterial adhesion. These findings illustrate that the T6SS of A. hydrophila NJ-35 is active, and the three Hcp family proteins take part in different processes in environmental adaptation and virulence of this bacterium. This study will provide valuable insights into our understanding of microbial interactions and thus contribute to a broader effort to manipulate these interactions for therapeutic or environmental benefit.
VI 型分泌系统 (T6SS) 被认为是细菌竞争和毒力的关键因素。溶细胞调节蛋白 (Hcp) 是 T6SS 的标志。嗜水气单胞菌中国流行株 NJ-35 中 Hcp 的分泌表明存在功能性 T6SS。在本研究中，在菌株 NJ-35 的基因组中鉴定出三个 hcp 基因拷贝。我们针对这些 Hcp 家族蛋白生成了缺失突变体。这些突变体在 Hcp 产生、与其他细菌或真核细胞的相互作用以及细菌毒力方面表现出不同的水平。Hcp1 对于 T6SS 组装是必需的，并且在细菌竞争中起主要作用；Hcp2 在生物膜形成和细菌黏附方面起负作用，更多地参与了嗜水气单胞菌在斑马鱼中的毒力和对四膜虫捕食的存活，Hcp3 则正向影响生物膜形成和细菌黏附。这些发现表明，嗜水气单胞菌 NJ-35 的 T6SS 是活跃的，并且这三种 Hcp 家族蛋白参与了该细菌在环境适应和毒力方面的不同过程。本研究将为我们理解微生物相互作用提供有价值的见解，并为操纵这些相互作用以实现治疗或环境效益的更广泛努力做出贡献。
