Open AccessAnalysis of the PilQ Secretin from Neisseria meningitidis by Transmission Electron Microscopy Reveals a Dodecameric Quaternary Structure
Author(s) -
Richard F. Collins,
Linn Davidsen,
Jeremy P. Derrick,
Robert C. Ford,
Tone Tønjum
Publication year - 2001
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.183.13.3825-3832.2001
Subject(s) - pilus , neisseria meningitidis , neisseria gonorrhoeae , pilin , biology , biophysics , microbiology and biotechnology , electron microscope , transmission electron microscopy , flagellum , materials science , optics , bacteria , virulence , biochemistry , physics , nanotechnology , genetics , gene
PilQ is a member of the secretin family of outer membrane proteins and is specifically involved in secretion of type IV pili inNeisseria meningitidis, Neisseria gonorrhoeae , andPseudomonas aeruginosa . The quaternary structure of PilQ fromN. 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 theN. gonorrhoeae pilin subunit, fitted neatly into the cavity, demonstrating how PilQ could serve as a channel for the growing pilus fiber.