Cryo-EM structure of the homohexameric T3SS ATPase-central stalk complex reveals rotary ATPase-like asymmetry

• Published in: Nature communications 2019-02, Vol.10 (1), p.626-12, Article 626
• Main Authors: Majewski, Dorothy D., Worrall, Liam J., Hong, Chuan, Atkinson, Claire E., Vuckovic, Marija, Watanabe, Nobuhiko, Yu, Zhiheng, Strynadka, Natalie C. J.
• Format: Article
• Language: English
• Subjects: 101/28; 631/326/22/1434; 631/326/41/2536; 631/45/535/1258/1259; 631/45/607/1164; 82/16; 82/29; 82/80; 82/83; Activation; Active sites; Adenosine triphosphatase; Atomic structure; Catalysis; Cryoelectron Microscopy - methods; Dysentery; E coli; Electrostatic properties; Escherichia coli Proteins - metabolism; Escherichia coli Proteins - ultrastructure; Fever; Glycerol; Gram-negative bacteria; Humanities and Social Sciences; multidisciplinary; Nosocomial infections; Pathogenicity; Pathogens; Plague; Protein Structure, Secondary; Proteins; Proton-Translocating ATPases - metabolism; Proton-Translocating ATPases - ultrastructure; Science; Science (multidisciplinary); Secretion; Substrates; Type III Secretion Systems - metabolism; Type III Secretion Systems - ultrastructure; Typhoid; Virulence; Waterborne diseases
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-08477-7

Many Gram-negative bacteria, including causative agents of dysentery, plague, and typhoid fever, rely on a type III secretion system – a multi-membrane spanning syringe-like apparatus – for their pathogenicity. The cytosolic ATPase complex of this injectisome is proposed to play an important role in energizing secretion events and substrate recognition. We present the 3.3 Å resolution cryo-EM structure of the enteropathogenic Escherichia coli ATPase EscN in complex with its central stalk EscO. The structure shows an asymmetric pore with different functional states captured in its six catalytic sites, details directly supporting a rotary catalytic mechanism analogous to that of the heterohexameric F 1 /V 1 -ATPases despite its homohexameric nature. Situated at the C-terminal opening of the EscN pore is one molecule of EscO, with primary interaction mediated through an electrostatic interface. The EscN-EscO structure provides significant atomic insights into how the ATPase contributes to type III secretion, including torque generation and binding of chaperone/substrate complexes. Many Gram-negative bacteria rely on a type III secretion system (T3SS) for their pathogenicity. Here authors present the cryo-EM structure of the E.coli T3SS ATPase-central stalk complex, which forms a homohexameric, asymmetric pore with different functional states.