Work

A ubiquitin-like protein controls assembly of a bacterial type VIIb secretion system

Year: 2025

Type: article

Abstract: Type VII secretion systems (T7SS) are protein translocation machines crucial for virulence and bacterial competition in Gram-positive bacteria. Despite their importance, the structural basis for assembly of type VIIb secretion systems (T7SSb), a widely distributed variant in Firmicutes, remains poorly understood. We present the cryo–electron microscopy structure of the T7SSb core complex from Bacillus subtilis , revealing how the ubiquitin-like protein YukD, coordinates assembly of the secretion machinery. YukD interacts extensively with the central channel component YukB and facilitates its association with the pseudokinase YukC, forming a stable building block for channel assembly. Time-lapse microscopy and competition assays demonstrate that YukD is essential for proper T7SSb complex formation and contact-dependent bacterial killing. Our findings reveal how bacteria have adapted a ubiquitin-like protein as a structural regulator for assembling a large secretion complex.

Source: Science Advances

DOI: 10.1126/sciadv.ady9587

Authors: Gabriel U. Oka, Nathanaël Benoit, Axel Siroy, Francesca Gubellini, Esther Marza, Rémi Fronzes