New Insights into the Assembly of Bacterial Secretins

• DOI: 10.1074/jbc.m112.432096
• Publication Date: 2012-11-28T04:07:07Z
• Authors: Ruben Van der Meeren; Yurong Wen; Patrick Van Gelder; Jan Tommassen; Bart Devreese; Savvas N. Savvides
• Keywords: Inner membrane; Multiprotein complex; Trimer

The type II secretion system is a multiprotein assembly spanning the inner and outer membranes in Gram-negative bacteria. It found almost all pathogenic bacteria where it contributes to virulence, host tissue colonization, infection. exoproteins are secreted across membrane via large translocation channel, secretin, which typically adopts dodecameric structure. These secretin channels have periplasmic N-terminal domains that reach out into periplasm for communication with platform pseudopilus structure spans periplasm. Here we report crystal of domain XcpQ from Pseudomonas aeruginosa, revealing two-lobe dimeric featuring parallel subunits engaging well defined interactions at tips each lobe. We employed structure-based engineering disulfide bridges native mass spectrometry show dimerizes concentration-dependent manner. Validation these insights context cellular full-length further evaluation functionality disulfide-linked establishes basic oligomerization unit dimer. This consistent notion assembles as hexamer dimers ensure correct projection Therefore, our studies provide key conceptual advancement understanding principles dynamic function secretins challenge recent reporting monomers subunit oligomer.