Effect of T6SS effector protein Clpv of Salmonella typhimurium on macrophage polarization

Abstract:

[Objective] To investigate the role of type VI secretion system (T6SS) effector protein Clpv in the pathogenesis of Salmonella typhimurium.[Methods] We cloned the clpv gene from SL1344 genome of S. typhimurium and compared it with the clpv genes of other Gram-negative bacteria (Pseudomonas taiwanensis, Raoultella planticola, Listonella anguillarum, Pantoea ananatis, Actinomyces viscosus, and Escherichia coli). The clpv gene was cloned into pEGFP-N1 vector to construct the recombinant plasmid pEGFP-Clpv. The protein expression, localization, and the induced M1 and M2 polarization of mouse macrophages were detected by Western blotting, q-PCR, fluorescence microscopy, and flow cytometry. [Results] The clpv gene was 2 637 bp, showing the highest homology to clpv of P. taiwanensis. Western blotting, q-PCR, and immunofluorescence showed that the recombinant protein was about 120 kDa and apparent green fluorescence in cells was found. The protein was located primarily in cell membrane. The results of q-PCR and flow cytometry indicated that Clpv enhanced M1 polarization (P<0.01) but weakened M2 polarization of mouse macrophages (P<0.01). [Conclusion] The T6SS effector protein Clpv of S. typhimurium was cloned and expressed, and its intracellular localization and effect on macrophage polarization were clarified.

Key words:Salmonella typhimurium;type VI secretion system;Clpv;expression localization;polarization