Structural insights into the assembly of the type III secretion needle complex.
Type III secretion systems (TTSSs) mediate translocation of virulence factors into host cells. We report the 17-angstrom resolution structures of a central component of Salmonella typhimurium TTSS, the needle complex, and its assembly precursor, the bacterial envelope-anchored base. Both the base and the fully assembled needle complex adopted multiple oligomeric states in vivo, and needle assembly was accompanied by recruitment of the protein PrgJ as a structural component of the base. Moreover, conformational changes during needle assembly created scaffolds for anchoring both PrgJ and the needle substructure and may provide the basis for substrate-specificity switching during type III secretion.
Marlovits
Thomas C
TC
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520-8024, USA.
Kubori
Tomoko
T
Sukhan
Anand
A
Thomas
Dennis R
DR
Galán
Jorge E
JE
Unger
Vinzenz M
VM
D001426:Bacterial Proteins / Q000737:chemistry / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D046911:Macromolecular Substances; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000648:ultrastructure; D012486:Salmonella typhimurium / Q000737:chemistry / Q000648:ultrastructure*
D001426:Bacterial Proteins; D046911:Macromolecular Substances; D026901:Membrane Transport Proteins; C079790:PrgH protein, Salmonella typhimurium; C090991:invG protein, Salmonella typhimurium