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Characterizing the Syphilis-Causing Treponema pallidum ssp. pallidum Proteome Using Complementary Mass Spectrometry
Osbak, K.K. Houston, S. Lithgow, K.V. Meehan, Conor J. Strouhal, M. Å majs, D. Cameron, C.E. Van Ostade, X. Kenyon, C.R. Van Raemdonck, G.A.
Osbak, K.K.
Houston, S.
Lithgow, K.V.
Meehan, Conor J.
Strouhal, M.
Å majs, D.
Cameron, C.E.
Van Ostade, X.
Kenyon, C.R.
Van Raemdonck, G.A.
Publication Date
2016-09
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© 2016 Osbak et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are
credited. http://creativecommons.org/licenses/by/4.0/
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2016-08-19
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Abstract
Background.
The spirochete bacterium Treponema pallidum ssp. pallidum is the etiological agent of
syphilis, a chronic multistage disease. Little is known about the global T. pallidum proteome,
therefore mass spectrometry studies are needed to bring insights into pathogenicity and
protein expression profiles during infection.
Methodology/Principal Findings.
To better understand the T. pallidum proteome profile during infection, we studied T. pallidum ssp. pallidum DAL-1 strain bacteria isolated from rabbits using complementary mass
spectrometry techniques, including multidimensional peptide separation and protein identification via matrix-assisted laser desorption ionization-time of flight (MALDI-TOF/TOF) and
electrospray ionization (ESI-LTQ-Orbitrap) tandem mass spectrometry. A total of 6033 peptides were detected, corresponding to 557 unique T. pallidum proteins at a high level of confidence, representing 54% of the predicted proteome. A previous gel-based T. pallidum MS
proteome study detected 58 of these proteins. One hundred fourteen of the detected proteins were previously annotated as hypothetical or uncharacterized proteins; this is the first
account of 106 of these proteins at the protein level. Detected proteins were characterized
according to their predicted biological function and localization; half were allocated into a
wide range of functional categories. Proteins annotated as potential membrane proteins
and proteins with unclear functional annotations were subjected to an additional bioinformatics pipeline analysis to facilitate further characterization. A total of 116 potential membrane proteins were identified, of which 16 have evidence supporting outer membrane
localization. We found 8/12 proteins related to the paralogous tpr gene family: TprB, TprC/D, TprE, TprG, TprH, TprI and TprJ. Protein abundance was semi-quantified using
label-free spectral counting methods. A low correlation (r = 0.26) was found between previous microarray signal data and protein abundance.
Conclusions.
This is the most comprehensive description of the global T. pallidum proteome to date.
These data provide valuable insights into in vivo T. pallidum protein expression, paving the
way for improved understanding of the pathogenicity of this enigmatic organism.
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Published version
Citation
Osbak KK, Houston S, Lithgow KV et al (2016) Characterizing the Syphilis-Causing Treponema pallidum ssp. pallidum Proteome Using Complementary Mass Spectrometry. PLoS Neglected Tropical Diseases. 10(9): e0004988.
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