Elgamoudi Bassam A, Starr Kirstie S, Korolik Victoria
Institute for Glycomics, Griffith University, Gold Coast, QLD 4222, Australia.
Microorganisms. 2022 Oct 14;10(10):2030. doi: 10.3390/microorganisms10102030.
Cyclic diguanosine monophosphate (c-diGMP) is a ubiquitous second messenger involved in the regulation of many signalling systems in bacteria, including motility and biofilm formation. Recently, it has been reported that c-di-GMP was detected in C. jejuni DRH212; however, the presence and the role of c-di-GMP in other C. jejuni strains are unknown. Here, we investigated extracellular c-di-GMP as an environmental signal that potentially triggers biofilm formation in C. jejuni NCTC 11168 using a crystal violet-based assay, motility-based plate assay, RT-PCR and confocal laser scanning microscopy (CLSM). We found that, in presence of extracellular c-di-GMP, the biofilm formation was significantly reduced (>50%) and biofilm dispersion enhanced (up to 60%) with no effect on growth. In addition, the presence of extracellular c-di-GMP promoted chemotactic motility, inhibited the adherence of C. jejuni NCTC 11168-O to Caco-2 cells and upregulated the expression of Cj1198 (luxS, encoding quarum sensing pathway component, autoinducer-2), as well as chemotaxis genes Cj0284c (cheA) and Cj0448c (tlp6). Unexpectedly, the expression of Cj0643 (cbrR), containing a GGDEF-like domain and recently identified as a potential diguanylate cyclase gene, required for the synthesis of c-di-GMP, was not affected. Our findings suggest that extracellular c-di-GMP could be involved in C. jejuni gene regulation, sensing and biofilm dispersion.
环二鸟苷单磷酸（c-diGMP）是一种普遍存在的第二信使，参与细菌中许多信号系统的调控，包括运动性和生物膜形成。最近，有报道称在空肠弯曲杆菌DRH212中检测到了c-di-GMP；然而，c-di-GMP在其他空肠弯曲杆菌菌株中的存在情况及其作用尚不清楚。在此，我们使用基于结晶紫的检测方法、基于运动性的平板检测方法、逆转录聚合酶链反应（RT-PCR）和共聚焦激光扫描显微镜（CLSM），研究了细胞外c-di-GMP作为一种可能触发空肠弯曲杆菌NCTC 11168生物膜形成的环境信号。我们发现，在细胞外c-di-GMP存在的情况下，生物膜形成显著减少（>50%），生物膜分散增强（高达60%），而对生长没有影响。此外，细胞外c-di-GMP的存在促进了趋化运动，抑制了空肠弯曲杆菌NCTC 11168-O对Caco-2细胞的黏附，并上调了Cj1198（luxS，编码群体感应途径成分自诱导物-2）以及趋化基因Cj0284c（cheA）和Cj0448c（tlp6）的表达。出乎意料的是，含有GGDEF样结构域且最近被鉴定为c-di-GMP合成所需的潜在二鸟苷酸环化酶基因的Cj0643（cbrR）的表达未受影响。我们的研究结果表明，细胞外c-di-GMP可能参与空肠弯曲杆菌的基因调控、感知和生物膜分散。
