Browsing by Subject "Outer membrane proteins"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Open Access
    Characterizing the syphilis-causing Treponema pallidum ssp. pallidum proteome using complementary mass spectrometry
    (Public Library of Science, 2016) Osbak, Kara K; Houston, Simon; Lithgow, Karen V; Meehan, Conor J; Strouhal, Michal; Šmajs, David; Cameron, Caroline E; Van Ostade, Xaveer; Kenyon, Chris R; Van Raemdonck, Geert A
    Author Summary: Syphilis remains a major cause of morbidity and mortality worldwide. The bacterium causing syphilis, Treponema pallidum ssp. pallidum , has evolved into a highly distinctive organism that is only able survive (and be propagated) in mammals. In humans it can evade the immune system for decades with devastating consequences. Much remains to be learned about how it accomplishes this. Only a minority of its predicted proteins have been detected experimentally thus far. We aimed to more comprehensively characterize the proteins of this organism. Since it cannot be cultured in vitro , we cultured T . pallidum in rabbits and analyzed extracted proteins using different mass spectrometry methods, a manner of detecting proteins with high accuracy. In total, we detected more than half of the predicted number of proteins that could be expressed by this bacterium (N = 557). For approximately half of the proteins, we succeeded in characterizing their predicted cellular location using an array of bioinformatic tools and catalogued their function. This is the most comprehensive analysis of the T . pallidum proteome to date. This study lays the groundwork for other protein investigations of this unique organism.
  • Thumbnail Image
    Item
    Open Access
    Identification of a collagen type I adhesin of Bacteroides fragilis
    (Public Library of Science, 2014) Galvão, Bruna P G V; Weber, Brandon W; Rafudeen, Mohamed S; Ferreira, Eliane O; Patrick, Sheila; Abratt, Valerie R
    Bacteroides fragilis is an opportunistic pathogen which can cause life threatening infections in humans and animals. The ability to adhere to components of the extracellular matrix, including collagen, is related to bacterial host colonisation. Collagen Far Western analysis of the B. fragilis outer membrane protein (OMP) fraction revealed the presence two collagen adhesin bands of ∼31 and ∼34 kDa. The collagen adhesins in the OMP fraction were separated and isolated by two-dimensional SDS-PAGE and also purified by collagen affinity chromatography. The collagen binding proteins isolated by both these independent methods were subjected to tandem mass spectroscopy for peptide identification and matched to a single hypothetical protein encoded by B. fragilis NCTC 9343 (BF0586), conserved in YCH46 (BF0662) and 638R (BF0633) and which is designated in this study as cbp1 (collagen binding protein). Functionality of the protein was confirmed by targeted insertional mutagenesis of the cbp1 gene in B. fragilis GSH18 which resulted in the specific loss of both the ∼31 kDa and the ∼34 kDa adhesin bands. Purified his-tagged Cbp1, expressed in a B. fragilis wild-type and a glycosylation deficient mutant, confirmed that the cbp1 gene encoded the observed collagen adhesin, and showed that the 34 kDa band represents a glycosylated version of the ∼31 kDa protein. Glycosylation did not appear to be required for binding collagen. This study is the first to report the presence of collagen type I adhesin proteins in B. fragilis and to functionally identify a gene encoding a collagen binding protein.