Listeria membrane protrusion collapse: Requirement of Cyclophilin A for Listeria cell-to-cell spreading.

Background. Listeria generate actin-rich tubular protrusions at the plasma membrane that propel the bacteria into neighboring cells. The precise molecular mechanisms governing the formation of these protrusions remain poorly defined. Methods. In this study, we demonstrate that the prolyl cis-trans isomerase (PPIase) cyclophilin A (CypA) is hijacked by Listeria at membrane protrusions used for cell-to-cell spreading. Results. Cyclophilin A localizes within the F-actin of these structures and is crucial for their proper formation, as cells depleted of CypA have extended actin-rich structures that are misshaped and are collapsed due to changes within the F-actin network. The lack of structural integrity within the Listeria membrane protrusions hampers the microbes from spreading from CypA null cells. Conclusions. Our results demonstrate a crucial role for CypA during Listeria infections.