Figure 1.

N-terminal labeling using SrtA_staph. (a) SrtA_staph catalyzes a transacylation reaction using labeled LPRT methyl esters as substrates. The labeled LPRT fragment is transferred to proteins containing N-terminal glycines in a site-specific fashion. (b) FITC (1) and biotin (2) LPRT methyl esters for N-terminal transacylation. (c) CtxB derivatives (50 μM) were treated with 500 μM 1 and 50 μM SrtA_staph for 2 h at 37 °C in 50 mM Tris (pH 7.5), 150 mM NaCl, and 10 mM CaCl₂. Reactions were analyzed by SDS-PAGE with visualization by coomassie staining and fluorescent gel scanning.