David L. Hagen
Member
Member # 323
|
posted 09. August 2006 13:57
In situ structure of the complete Treponema primitia
Gavin E. Murphy1, Jared R. Leadbetter2 and Grant J. Jensen1
Nature advance online publication 2 August 2006 | doi:10.1038/nature05015; Received 7 April 2006; Accepted 21 June 2006; Published online 2 August 2006
The bacterial flagellar motor is an amazing nanomachine: built from approximately 25 different proteins, it uses an electrochemical ion gradient to drive rotation at speeds of up to 300 Hz (refs 1, 2). The flagellar motor consists of a fixed, membrane-embedded, torque-generating stator and a typically bidirectional, spinning rotor that changes direction in response to chemotactic signals. Most structural analyses so far have targeted the purified rotor3,4, and hence little is known about the stator and its interactions. Here we show, using electron cryotomography of whole cells, the in situ structure of the complete flagellar motor from the spirochaete Treponema primitia at 7 nm resolution. Twenty individual motor particles were computationally extracted from the reconstructions, aligned and then averaged. The stator assembly, revealed for the first time, possessed 16-fold symmetry and was connected directly to the rotor, C ring and a novel P-ring-like structure. The unusually large size of the motor suggested mechanisms for increasing torque and supported models wherein critical interactions occur atop the C ring, where our data suggest that both the carboxy-terminal and middle domains of FliG are found.
1. Division of Biology and
2. Division of Environmental Science and Engineering, California Institute of Technology, Pasadena, California 91125, USA
Correspondence to: Grant J. Jensen1 Correspondence and requests for materials should be addressed to G.J.J. (Email: jensen@caltech.edu).The averaged and symmetrized structure has been deposited in the EM Data Bank (http://www.ebi.ac.uk/msd/index.html) with the accession code EMD-1235.
Full Article: In situ structure of the complete Treponema primitia
IP: Logged
|
Printer-friendly view of this topic