Year: 2009
Type: article
Abstract: Type IV secretion systems (T4SSs) are molecular machines used for the transport of macromolecules across the bacterial cell envelope in Gram-negative bacteria.T4SSs are highly versatile.Conjugative T4SSs translocate DNA from a donor to a recipient bacterium and contribute to bacterial genome plasticity, spread of antibiotic resistance or other virulence trait among bacterial pathogens.In some bacteria such as Helicobacter pylori (Cag PI), Brucella suis (VirB/D), or Legionella pneumophila (Dot, Icm), T4SSs are directly involved in pathogenicity as they mediate the secretion of virulence factors (DNA or toxins) into host cells.The archetypal T4SS, the VirB/D system, was defined in Agrobacterium tumefaciens where it is naturally responsible for the delivery of the T-DNA to the plant host-cell.The A. tumefasciens VirB/D system comprises 12 proteins (VirB1 to 11 and VirD4).In the past few years, atomic structures of isolated components such as VirD4, VirB11, VirB5, virB8, virB10 and virB9 have become available and have provided seminal insights into the mechanism of T4SS assembly and substrate secretion.However, no structural data was available concerning the assembly of the complex, particularly at the level of both bacterial membranes where the T4SS is supposed to form pores/channels.We here present the cryoEM structure of a 1 MDa complex composed of VirB7, VirB9 and VirB10 homologues from the E. coli conjugative plasmid pKM101 T4SS.The molecular characterization of this ternary complex provides key insights into the type IV secretion systems architecture and assembly
Authors: Remi Fronzes, Gabriel Waksman
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2323603606