Stretching the arms of the type VI secretion sheath protein

Abstract

The bacterial type VI secretion system (T6SS) is a multicomponent complex responsible for the translocation of effector proteins into the external milieu. The T6SS consists of an external sheath, an internal rigid tube, a baseplate, and a T6SS‐specific membrane complex. Secretion is accomplished by the contraction of the sheath, which expels the effector‐loaded tube. In this issue of EMBO reports , Brackmann et al [[1][1]] show how modifications of the sheath subunits can lock the T6SS assembly in the extended state. These findings allowed Wang et al [[2][2]] and Nazarov et al [[3][3]] to purify the T6SS sheath–tube–baseplate complex in the extended pre‐secretion state and to analyze its structure using cryo‐electron microscopy (cryoEM). EMBO Reports (2018) e45627 [1]: #ref-1 [2]: #ref-2 [3]: #ref-3