Sortases from a Probiotic Lactobacillus rhamnosus GG: Cloning, Expression, Purification, Crystallization and Preliminary X-Ray Diffraction Study

Sortases are membrane-associated cysteine transpeptidases found mainly in Gram-positive bacteria. They have been intensely studied in pathogenic strains as they play a key role in covalent attachment of various virulence-associated surface proteins including pili to the cell wall and also in biogenesis of pili. The recent identification of sortase genes in some members of gut microbiota indicates their likely role in establishing interaction with the human gastrointestinal tract for probiotic traits. While the structural information about sortases thus far is limited to pathogenic bacteria, here we have the produced recombinant form of housekeeping (SrtA) and pilin-specific (SrtC1) sortases from gut-adapted probiotic strain Lactobacillus rhamnosus GG and crystallized them. The crystals of SrtA and SrtC1 diffracted to a resolution of 1.9 angstrom and belonged to monoclinic and tetragonal crystal forms respectively.