How the adherens junction proteins PLEKHA7 and PDZD11 regulate Staphylococcus aureus α-toxin cytotoxicity

In a genetic screen, PLEKHA7, and other junctional proteins were identified as host factors mediating death by S.aureus α-toxin. Here, I clarify the underlying molecular mechanism using cell biological and biochemical methods. In summary, I identified a macromolecular complex that consists of PLEKHA7-PDZD11-tetraspanin33-afadin that clusters α-toxin receptor ADAM10 at the apical junctions through a dock-and-lock mechanism. In addition, I also identified a pool of ADAM10 that is distributed on the lateral surfaces, and which is independent of PLEKHA7-PDZD11 complex. Junctionally clustered ADAM10 seeds the formation of stable α-toxin pores, resulting in prolonged injury and cell death. The disruption of PLEKHA7-PDZD11 complex inhibits the formation of junctionally clustered ADAM10 and toxin pores. And the laterally distributed toxin pores are unstable and are removed by macropinocytosis, causing intrinsically weaker injury, resulting in cell recovery and survival. Thus I identify a novel mechanism through which cell junction proteins regulate S.aureus α-toxin cytotoxicity