Fluorescent substrates for bacterial proteases

Sortases - a family of Gram-positive transpeptidases

Sortases are responsible for anchoring surface protein virulence factors to the peptidoglycan cell wall layer.

Sortase cleaves surface proteins at the LPXTG motif and catalyzes the formation of an amide bond between the carboxyl group of threonine and the amino group of cell-wall cross-bridges.

The LPXTG motif is conserved in more than 100 surface proteins of Gram-positive pathogens.

Cleavage of FRET substrates by sortase reveals a fluorescent signal that may be measured to study sortase activity. Inhibition of the sortase activity is a potential way of treatment of the staphylococcal infection.