Interaction of RTX toxins with the host cell plasma membrane

Repeats in ToXins (RTX) protein family is a group of exoproteins secreted by Type 1 secretion system (T1SS) of several Gram-negative bacteria. The term RTX is derived from the characteristic nonapeptide sequence (GGxGxDxUx) present at the C-terminus of the protein. This RTX domain binds to calcium ions in the extracellular medium after being secreted out of the bacterial cells, and this facilitates folding of the entire protein. The secreted protein then binds to the host cell membrane and forms pores via a complex pathway, which eventually leads to the cell lysis. In this review, we summarize two different pathways in which RTX toxins interact with host cell membrane and discuss the possible reasons for specific and unspecific activity of RTX toxins to different types of host cells.

Automated summary

The RTX protein family is a group of exoproteins secreted by the Type 1 secretion system (T1SS) of certain Gram-negative bacteria. It is characterized by a nonapeptide sequence (GGxGxDxUx) at the C-terminus. The RTX domain binds to calcium ions in the extracellular medium, leading to proper protein folding. The secreted protein then interacts with the host cell membrane, forming pores and causing cell lysis. This review summarizes the different pathways of RTX toxins' interaction with host cell membrane and discusses the reasons for their specific or nonspecific activity towards different host cell types.