Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Argentina.
Cell Microbiol. 2019 Sep;21(9):e13045. doi: 10.1111/cmi.13045. Epub 2019 May 31.
Serratia marcescens is an opportunistic pathogen with increasing incidence in clinical settings. This is mainly attributed to the timely expression of a wide diversity of virulence factors and intrinsic and acquired resistance to antibiotics, including β-lactams, aminoglycosides, quinolones, and polypeptides. For these reasons, S. marcescens has been recently categorised by the World Health Organization as one priority to strengthen efforts directed to develop new antibacterial agents. Therefore, it becomes critical to understand the underlying mechanisms that allow Serratia to succeed within the host. S. marcescens ShlA pore-forming toxin mediates phenotypes that alter homeostatic and signal transduction pathways of host cells. It has been previously demonstrated that ShlA provokes cytotoxicity, haemolysis and autophagy and also directs Serratia egress and dissemination from invaded nonphagocytic cells. However, molecular details of ShlA mechanism of action are still not fully elucidated. In this work, we demonstrate that Ni selectively and reversibly blocks ShlA action, turning wild-type S. marcescens into a shlA mutant strain phenocopy. Combined use of Ni and calcium chelators allow to discern ShlA-triggered phenotypes that require intracellular calcium mobilisation and reveal ShlA function as a calcium channel, providing new insights into ShlA mode of action on target cells.
粘质沙雷氏菌是一种机会性病原体，在临床环境中的发病率不断上升。这主要归因于其能够及时表达广泛多样的毒力因子，以及对包括β-内酰胺类、氨基糖苷类、喹诺酮类和多肽类在内的抗生素产生固有和获得性耐药性。由于这些原因，粘质沙雷氏菌最近被世界卫生组织列为优先事项之一，以加强努力开发新的抗菌药物。因此，了解允许沙雷氏菌在宿主中成功的潜在机制变得至关重要。沙雷氏菌 ShlA 孔形成毒素介导改变宿主细胞内稳态和信号转导通路的表型。先前已经证明 ShlA 可引起细胞毒性、溶血和自噬，还可指导沙雷氏菌从被入侵的非吞噬细胞中逸出和扩散。然而，ShlA 作用机制的分子细节仍未完全阐明。在这项工作中，我们证明 Ni 选择性和可逆地阻断了 ShlA 的作用，使野生型粘质沙雷氏菌变成了 shlA 突变株表型的复制品。Ni 和钙螯合剂的联合使用可以区分需要细胞内钙动员的 ShlA 触发表型，并揭示 ShlA 作为钙通道的功能，为 ShlA 对靶细胞的作用模式提供了新的见解。
