Characterizing the Syphilis-Causing Treponema pallidum ssp. pallidum Proteome Using Complementary Mass Spectrometry.
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.



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.



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.
HIV/STI Unit, Institute of Tropical Medicine, Antwerp, Belgium.
Kara K
0000-0002-8612-8413
KK
Osbak
Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
Simon
S
Houston
Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
Karen V
KV
Lithgow
Unit of Mycobacteriology, Institute of Tropical Medicine, Antwerp, Belgium.
Conor J
CJ
Meehan
Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Michal
M
Strouhal
Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.
David
D
Šmajs
Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
Caroline E
CE
Cameron
Laboratory for Protein Science, Proteomics and Epigenetic Signaling (PPES) and Centre for Proteomics (CFP), University of Antwerp, Wilrijk, Belgium.
Xaveer
X
Van Ostade
HIV/STI Unit, Institute of Tropical Medicine, Antwerp, Belgium.|Division of Infectious Diseases and HIV Medicine, University of Cape Town, Cape Town, South Africa.
Chris R
CR
Kenyon
HIV/STI Unit, Institute of Tropical Medicine, Antwerp, Belgium.|Laboratory for Protein Science, Proteomics and Epigenetic Signaling (PPES) and Centre for Proteomics (CFP), University of Antwerp, Wilrijk, Belgium.
Geert A
GA
Van Raemdonck
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D020543:Proteome / Q000032:analysis*; D011817:Rabbits; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013587:Syphilis / Q000382:microbiology; D053719:Tandem Mass Spectrometry; D014210:Treponema pallidum / Q000235:genetics*
D001426:Bacterial Proteins; D020543:Proteome