US Patent 7101692 Identification of sortase gene

The present invention is a substantially purified sortase-transamidase enzyme from Gram-positive bacteria, such as Staphylococcus aureus. A specific sortase-transamidase enzyme disclosed has a molecular weight of about 29,076 daltons and catalyzes a reaction that covalently cross-links the carboxyl terminus of a protein having a sorting signal to the peptidoglycan of a Gram-positive bacterium, where the sorting signal has a a motif of NPQ/KTN/G therein. Variants of the enzyme, methods for cloning the gene encoding the enzyme and expressing the cloned gene, and methods of use of the enzyme, including for screening for antibiotics and for display of proteins or peptides on the surfaces of Gram-positive bacteria, are also disclosed.