Figure 3.

Close-up of the catalytic core of SseK3. A, sequence alignment of the SseK effectors family and their E. coli ortholog NleB. The conserved residues involved in the metal coordination, including the DXD motif, are reported as magenta dots on the sequence alignment. Shown are close-ups of the residues that participate in the coordination of the Mn²⁺ ion (B) and in the ligand interaction (C). D, downfield region of the proton NMR spectra of SseK3, showing that the addition of Mg²⁺ and UDP-GlcNAc quashes the sharp resonances present in the spectrum of unbound SseK3. The asterisks show the resonances from a complex multiplet around 6 ppm originating from the UDP-GlcNAc (green) and the resonance at 10 ppm from the Hϵ1 of Trp-334 (blue).