Type VI secretion and bacteriophage tail tubes share a common assembly pathway.

TitleType VI secretion and bacteriophage tail tubes share a common assembly pathway.
Publication TypeJournal Article
Year of Publication2014
AuthorsBrunet YR, Hénin J, Celia H, Cascales E
JournalEmbo Rep.
Volume15
Pagination315–21
Date Publishedmar
ISSN1469-3178
KeywordsAmino Acid Sequence, Bacterial Secretion Systems, Escherichia coli, Escherichia coli Proteins, Molecular Sequence Data, Protein Binding, Protein Multimerization, Protein Structure, Tertiary, Virulence Factors
Abstract

The Type VI secretion system (T6SS) is a widespread macromolecular structure that delivers protein effectors to both eukaryotic and prokaryotic recipient cells. The current model describes the T6SS as an inverted phage tail composed of a sheath-like structure wrapped around a tube assembled by stacked Hcp hexamers. Although recent progress has been made to understand T6SS sheath assembly and dynamics, there is no evidence that Hcp forms tubes in vivo. Here we show that Hcp interacts with TssB, a component of the T6SS sheath. Using a cysteine substitution approach, we demonstrate that Hcp hexamers assemble tubes in an ordered manner with a head-to-tail stacking that are used as a scaffold for polymerization of the TssB/C sheath-like structure. Finally, we show that VgrG but not TssB/C controls the proper assembly of the Hcp tubular structure. These results highlight the conservation in the assembly mechanisms between the T6SS and the bacteriophage tail tube/sheath.

DOI10.1002/embr.201337936
Citation Key2014|1645