Characterization of the sortase A from Lactobacillus acidophilus ATCC 4356 involved in adherence to intestinal cells

Aim: Confirmation of the enzymatic activity of Class A sortase (SrtA) in probiotic strain Lactobacillus acidophilus associated with the adhesion properties. Materials & methods: SrtA from L. acidophilus ATCC 4356 was purified and its enzymatic properties was investigated by site-directed mutagenesis approach and the sensitivity to metal ions was also detected. Results: SrtA of L. acidophilus ATCC4356 can recognize LPxTG and LPxTD sorting motifs. The active sites of SrtA include His137, Cys198 and Arg205. Furthermore, acacetin can increase the activity of SrtA, while phenyl vinyl sulfone could effectively inhibit the activity of SrtA with an IC₅₀ of 143.32 μg/ml. The adhesion ability of L. acidophilus was also decreased resulting from the inhibition of SrtA activity. Conclusion: The unique properties of SrtA of L. acidophilus can provide some insights into the development of high-adhesion Lactobacillus strains in the GI tract.