Microbiology Editor's Choice: A new player in Salmonella type three secretion

Posted on January 2, 2019   by Microbiology Society

Each month, a manuscript published in our flagship journal Microbiology is chosen by a member of the Editorial Board. This month, the paper is "SrcA is a chaperone for the Salmonella SPI-2 type three secretion system effector SteD" and was chosen by Victor Cid.


In this article, Godlee et al. convincingly define the role of the Salmonella enterica ser. Typhimurium protein SrcA as a chaperone for the SPI-2 effector SteD via type 3 secretion (T3SS). This allows Salmonella to interfere with mature Major Histocompatibility Complex class II (mMHCII) expression at the plasma membrane of infected antigen-presenting cells. SrcA had previously been assigned a role as chaperone of other SPI-2 T3SS effectors, but this work refutes that idea, demonstrating that SrcA is involved in SteD stability, secretion and translocation.

SrcA is a chaperone for the Salmonella SPI-2 type three secretion system effector SteD

During infection, Salmonella uses a type three secretion system to deliver effector proteins into host cells. Many effectors require bacterial-encoded chaperones for delivery by the secretion system. One of these effectors, called SteD, decreases antigen presentation by dendritic cells.

In this study we found that SrcA, previously proposed as a chaperone for two other effectors, is also required for this activity. We demonstrated that SrcA is a chaperone for SteD, explaining its requirement for SteD function. A direct interaction between SrcA and SteD is necessary for the stability of SteD in Salmonella and for its delivery into host cells.

To access the full paper, click here. Editor's Choice articles published in Microbiology are free to read.