Comparative Proteomic Analysis of Shigella flexneri and Its Outer Membrane Vesicle

Purpose To gain a further understanding of the biological activity that Shigella flexneri exports via outer membrane vesicles(OMVS), we performed comparative proteomics analysis of protein profiles between bacteria and its outer membrane vesicles in response to temperature.Method Wild-type S. flexneir 2a strain 301 and its outer membrane vesicle respectively grown at 37 ℃ and 30 ℃were collected by sequential centrifugation. Furtherly, OMVs sample were purified by density gradient ultracentrifugation.Then the four samples were subject to shotgun proteomicanalysis by two-dimensional UPLC-linear ion trap mass spectrometry system.Results Total 1 510, 231,281 and 1 412 proteins were detected in bacteria itself and outer membrane vesicle grown at 37 ℃ and 30 ℃respectively.Of which, 156 proteins were common in all four samples. Further bioinformatics analysis found that there were specifically rich in COG categories of ribosomal structure and cell membrane biogenesis in the outer membrane vesicles samples. Besides,OMVs derived from strains grown at 37 ℃ specifically packaged a large number of Mxi-Spa type Ⅲ secretion system effectors.Conclusion Utilizing comparative proteomics technology, this study analyzed the changes of proteome of S. flexneri and its OMVs grown at different temperature for the first time and found some unique temperature-related vesicular proteins.Additionally, those selective cargo proteins detected in OMVs could serve as the groundwork for further disclosing OMV's selective package.