Department of Clinical Laboratory, Qidong People's Hospital, Qidong, Jiangsu, 226200, China.
Department of Clinical Laboratory, Nantong Third People's Hospital, Affiliated Nantong Hospital 3 of Nantong University, Nantong, Jiangsu, 226006, China.
Arch Microbiol. 2024 Jun 22;206(7):321. doi: 10.1007/s00203-024-04060-x.
Vibrio parahaemolyticus possesses two distinct type VI secretion systems (T6SS), namely T6SS1 and T6SS2. T6SS1 is predominantly responsible for adhesion to Caco-2 and HeLa cells and for the antibacterial activity of V. parahaemolyticus, while T6SS2 mainly contributes to HeLa cell adhesion. However, it remains unclear whether the T6SS systems have other physiological roles in V. parahaemolyticus. In this study, we demonstrated that the deletion of icmF2, a structural gene of T6SS2, reduced the biofilm formation capacity of V. parahaemolyticus under low salt conditions, which was also influenced by the incubation time. Nonetheless, the deletion of icmF2 did not affect the biofilm formation capacity in marine-like growth conditions, nor did it impact the flagella-driven swimming and swarming motility of V. parahaemolyticus. IcmF2 was found to promote the production of the main components of the biofilm matrix, including extracellular DNA (eDNA) and extracellular proteins, and cyclic di-GMP (c-di-GMP) in V. parahaemolyticus. Additionally, IcmF2 positively influenced the transcription of cpsA, mfpA, and several genes involved in c-di-GMP metabolism, including scrJ, scrL, vopY, tpdA, gefA, and scrG. Conversely, the transcription of scrA was negatively impacted by IcmF2. Therefore, IcmF2-dependent biofilm formation was mediated through its effects on the production of eDNA, extracellular proteins, and c-di-GMP, as well as its impact on the transcription of cpsA, mfpA, and genes associated with c-di-GMP metabolism. This study confirmed new physiological roles for IcmF2 in promoting biofilm formation and c-di-GMP production in V. parahaemolyticus.
副溶血性弧菌拥有两种截然不同的 VI 型分泌系统（T6SS），分别为 T6SS1 和 T6SS2。T6SS1 主要负责黏附 Caco-2 和 HeLa 细胞，并赋予副溶血性弧菌抗菌活性，而 T6SS2 主要促进 HeLa 细胞黏附。然而，T6SS 系统在副溶血性弧菌中是否具有其他生理作用尚不清楚。在本研究中，我们证实了 T6SS2 的结构基因 icmF2 的缺失会降低副溶血性弧菌在低盐条件下的生物膜形成能力，这一现象还受到孵育时间的影响。然而，icmF2 的缺失并不影响副溶血性弧菌在类似海洋的生长条件下的生物膜形成能力，也不影响鞭毛驱动的泳动和群集运动。我们发现 IcmF2 可促进生物膜基质的主要成分（包括细胞外 DNA [eDNA]和细胞外蛋白）和副溶血性弧菌中环二鸟苷酸（c-di-GMP）的产生。此外，IcmF2 正向影响 cpsA、mfpA 以及 scrJ、scrL、vopY、tpdA、gefA 和 scrG 等几个 c-di-GMP 代谢相关基因的转录。相反，IcmF2 负向影响 scrA 的转录。因此，icmF2 依赖的生物膜形成是通过其对 eDNA、细胞外蛋白和 c-di-GMP 的产生以及对 cpsA、mfpA 和 c-di-GMP 代谢相关基因的转录的影响来介导的。本研究证实了 IcmF2 在促进副溶血性弧菌生物膜形成和 c-di-GMP 产生方面的新的生理作用。
