Analysis of the PilQ secretin from Neisseria meningitidis by transmission electron microscopy reveals a dodecameric quaternary structure

R. F. Collins, L. Davidsen, J. P. Derrick, R. C. Ford, T. Tønjum

    Research output: Contribution to journalArticlepeer-review

    Abstract

    PilQ is a member of the secretin family of outer membrane proteins and is specifically involved in secretion of type IV pill in Neisseria meningitidis, Neisseria gonorrhoeae, and Pseudomonas aeruginosa. The quaternary structure of PilQ from N. meningitidis was analyzed by transmission electron microscopy by using a negative stain. Single particle averaging was carried out with a total data set of 650 individual particles, which produced a projection map generated from 296 particles at an estimated resolution of 2.6 nm. Oligomeric PilQ adopts a donut-like structure with an external ring that is 16.5 nm in diameter surrounding a central cavity that is 6.5 nm in diameter. Self-rotation and power spectrum analysis demonstrated the presence of 12-fold rotational symmetry, showing that PilQ is organized as a ring of 12 identical subunits. A model of the type IV meningococcal pilus fiber, based on the X-ray crystal structure of the N. gonorrhoeae pilin subunit, fitted neatly into the cavity, demonstrating how PilQ could serve as a channel for the growing pilus fiber.
    Original languageEnglish
    Pages (from-to)3825-3832
    Number of pages7
    JournalJournal of Bacteriology
    Volume183
    Issue number13
    DOIs
    Publication statusPublished - 2001

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