The assay, however, also suffered from issues of cross-reactivity with similar non-toxigenic Clostridium species . Finally, we have previously described a mass spectrometry-based activity detection assay, the Endopep-MS method, which
was developed to detect the activity of BoNTs in vitro against toxin-specific substrate peptides. This method was successful at detecting all seven BoNT serotypes . Proteomics has been used to study changes after treatment with BoNT/A on suprachiasmatic nucleus , on the thyroarytenoid muscle , and of C3 exoenzyme from C. botulinum , but there are very few reports on the BoNT proteome. In the present report, we detail proteomics methods that were successfully applied to the analysis of BoNT/G complex and thus further the understanding of the serotype. We confirmed the detection of toxin activity by click here use of the Endopep-MS method. The application of a rapid digestion method, coupled with nano ultra-pressure liquid chromatography tandem mass spectrometry (nUPLC-MS/MS), was successful at obtaining a greater percentage of amino acid sequence coverage of each protein associated with the/G complex than was previously reported. In addition, we describe the characterization and relative quantification of the proteins present in the/G complex. DNA Damage inhibitor We also compare BoNT/G to other BoNT serotypes and Selleckchem Trichostatin A discuss the previous literature reports to provide a complete description of the
BoNT/G complex. Results Amino acid sequence comparisons confirmed BoNT/G and/B similarity Phenetic analysis of the seven available toxin sequences compared revealed that BoNT/G was the most similar to the BoNT/B Okra and the least similar to BoNT/C Stockholm, with a 58.2% and a 32.9% sequence similarity, respectively (Figure 3A, additional file 1). To determine selleck chemical the extent to which the/G sequence is shared among toxins in the/B family,/G was compared with 22 different/B strains, including subtypes of/B1,/B2,/B3, bivalent (Bv/A and Bv/F), and non-proteolytic/B (np/B).
Of the 22 sequences,/G shared the most sequence homology with the/B2 Prevot 25 NCASE strain, with an overall 58.9% sequence similarity (additional file 2). In a focused look at the similarities between/G and the/B2 strain, the individual domains of the toxin proteins were compared. The percent similarity returned for each domain were as follows: peptidase (light chain) 60.9%, translocation (heavy chain) 63.8%, binding N-terminal (NT) (heavy chain) 55.3%, and binding C-terminal (CT) (heavy chain) 52.4% (Figure 3B). Additional comparison of BoNT/G NAPs with the NAPs of the other six serotypes indicated that not only is the type/G toxin sequence the most similar to/B, but the NAPs sequences for both serotypes do as well. The percent similarity returned for the NAPs were as follows: NTNH 78.3%, HA70 73.1% and HA17 58.7% (Figure 3C-D, additional files 3, 4, and 5).