[Erh-Min Lai] Effector onboard activating T6SS assembly

The type VI secretion system (T6SS) is a molecular nanomachine used by many bacteria for pathogenesis or bacterial competition by injecting effectors into the target cells. Because activities associated with T6SS are often costly, T6SS must be tightly regulated. However, our knowledge regarding how T6SS assembly and contraction are regulated remains limited. Using the plant pathogen Agrobacterium tumefaciens, Erh-Min Lai  and colleagues show that effectors are not just passengers but their loading onto the carriers also activate T6SS assembly. They demonstrated a new mechanism that applies across the A. tumefaciens group of bacteria. This is potentially a widespread mechanism, which may be deployed by many T6SS-possessing bacteria as a strategy for efficacious T6SS firing to ensure that effectors are loaded onto T6SS prior to completing its assembly.

This work is mainly contributed by two co-first authors, former Ph.D. student Dr. Chih-Feng Wu and former master student Yun-Wei Lien, and published in the journal EMBO Reports (Wu, Lien et al., 2019). Other authors contributed to this work include former Ph.D. student Devanand Bondage, former postdoc Jer-Sheng Lin, Shih-Yu Ling at the Institute of Biological Chemistry, Academia Sinica , Jeff Chang at Oregon State University  , and Martin Pilhofer at ETH, Zürich.