The type IX secretion system (T9SS) is the most recently discovered secretion system in the gram-negative bacteria and is specific to the Bacteroidetes phylum. It is comprised of at least 19 proteins, which together allows for the secretion and cell surface attachment of a specific group of proteins (T9SS substrates), that harbor a signal sequence at the C-terminus. Here we describe the structural characterization of the PorK, PorN and PorG components of the Porphyromonas gingivalis T9SS using electron microscopy and cross-linking mass spectrometry.
Keywords: Cross-linking; Electron microscopy; Gradient centrifugation; Mass spectrometry; PorG; PorK; PorN; Porphyromonas gingivalis; Protein complexes; Type IX secretion system (T9SS).