Organization and coordinated assembly of the type III secretion export apparatus

• Published in: Proceedings of the National Academy of Sciences - PNAS 2010-10, Vol.107 (41), p.17745-17750
• Main Authors: Wagner, Samuel, Königsmaier, Lisa, Lara-Tejero, Maria, Lefebre, Matthew, Marlovits, Thomas C., Galán, Jorge E.
• Format: Article
• Language: English
• Subjects: Antibodies; Bacteria; Bacterial Proteins - metabolism; Biochemistry; Biological Sciences; Blotting, Western; Cryoelectron Microscopy; Eukaryotes; Image Processing, Computer-Assisted; Immunoprecipitation; Materials; Membrane proteins; Membrane Transport Proteins - metabolism; Membranes; Microscopy; Multiprotein Complexes - metabolism; Multiprotein Complexes - ultrastructure; Protein secretion; Protein subunits; Proteins; Salmonella typhimurium; Salmonella typhimurium - metabolism; Salmonella typhimurium - physiology; Salmonella typhimurium - ultrastructure; Secretion; Secretory Pathway - physiology; Western blotting
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1008053107

Type III protein secretion systems are unique bacterial nanomachines with the capacity to deliver bacterial effector proteins into eukaryotic cells. These systems are critical to the biology of many pathogenic or symbiotic bacteria for insects, plants, animals, and humans. Essential components of these systems are multiprotein envelope-associated organelles known as the needle complex and a group of membrane proteins that compose the so-called export apparatus. Here, we show that components of the export apparatus associate intimately with the needle complex, forming a structure that can be visualized by cryo-electron microscopy. We also show that formation of the needle complex base is initiated at the export apparatus and that, in the absence of export apparatus components, there is a significant reduction in the levels of needle complex base assembly. Our results show a substantial coordination in the assembly of the two central elements of type III secretion machines.