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Microcin S, a Class II microcin produced by probiotic E. coli G3/10

This part contains the sequence for the antimicrobial protein microcin S (MccS).

Biology

Microcins are a subclass of antibacterial proteins known as bacteriocins, which have have in recent years garnered a significant amount of interest as antibiotic candidates due to their high antibacterial potency against drug-resistant bacterial as well as their narrow-spectrum antibacterial activity being potentially less harmful to our commensal microbiota [1]. Microcins are small, enterobacteria-produced bacteriocins that exert antibacterial activity against closely-related species, and microcin S is produced by Escherichia coli G3/10 which is present in the probiotic drug Symbioflor 2 that has been shown to successfully treat gastrointestinal disorders [2].

Zschüttig et al., the team which originally discovered and characterized MccS, discovered the gene encoding for the protein as well as its corresponding resistance gene in the E. coli G3/10 megaplasmid pSYM1. Enteropathogenic E. coli strains that were cloned with the MccS-coding gene was shown to be significantly less able to adhere to human intestinal epithelial cell lines upon the induction of MccS production [2].

In 2012, Hwang et al. more conclusively proved the antibacterial potency of MccS. They fused the protein YebF, which is able to facilitate the export of passenger proteins via the Sec and Omp pathways, to the N-terminal of MccS, and cloned the gene encoding for this fusion protein along with the MccS resistance gene into E. coli TOP10 and was able to use this engineered strain of E. coli to effectively kill the pathogenic Pseudomonas aeruginosa strain PAO1 [3][4].

Usage

We are interested in the antibacterial activity of MccS against antibiotic-resistant strains of bacteria found in urinary tract infections, namely E. coli and P. aeruginosa. However, in the interest of lab usage safety, for our wet lab work we will only test the antibacterial potency of MccS against Biosafety Level 1 laboratory strains of E. coli and P. putida.

References

[1] Cotter, P.D., Ross, R.P. & Hill, C., 2013. Bacteriocins - a viable alternative to antibiotics? Nature reviews. Microbiology, 11(2), pp.95–105. Available at: http://www.ncbi.nlm.nih.gov/pubmed/23268227.

[2] Zschüttig, A. et al., 2012. Identification and characterization of microcin S, a new antibacterial peptide produced by probiotic Escherichia coli G3/10. PLoS ONE, 7(3), pp.1–9.

[3] Prehna, G. et al., 2012. A protein export pathway involving Escherichia coli porins. Structure, 20(7), pp.1154–1166. Available at: http://dx.doi.org/10.1016/j.str.2012.04.014.

[4] Hwang, I.Y. et al., 2014. Reprogramming microbes to be pathogen-Seeking killers. ACS Synthetic Biology, 3(4), pp.228–237.