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Figure 9
Proposed model of PGN recognition by P60_tth. (a) PGN recognition model depicting how the LysM domain interacts with a PGN fragment. Each MurNAc is linked to a peptide [L-Ala-γ-D-Gln-L-Lys-(D-Asn)]; the MurNAc-peptide molecule was extracted from the L,D-carboxypeptidase crystal structure (PDB entry 4oxd ; Hoyland et al., 2014BB17). (b) Distances observed between cross-linked PGN strands and the length of the peptide stem in the three-dimensional model of S. aureus PGN proposed by Meroueh et al. (2006BB30). The distance between the two LysM binding sites in the P60_tth full-length crystal structure and between the entrance of the two active sites (red) of the P60_tth catalytic domains are also indicated. (c) Scheme explaining how the P60_tth homodimer could anchor the protein onto PGN. The PGN GlcNAc-MurNAc strands are represented by hexagons and the cross-linked peptide-stem composition of T. thermophilus is indicated by three-letter amino-acid codes; the amino-acid composition has been described previously (Quintela et al., 1995BB35). `Cys' represents the catalytic cysteines and the red arrows indicate the putative cleavage sites in the peptide stem.

Journal logoBIOLOGICAL
CRYSTALLOGRAPHY
ISSN: 1399-0047
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