FIG. 13.

Schematic structure of the membrane-bound SxxK subclass B3 PBP fusion protein Eco3 of E. coli. Spatial disposition along the polypeptide chain of the essential S*307 of the SxxK motif of the acyltransferase module (see Fig. 7) and of motifs 1, 2, and 3 (identified by the residue at the amino side of the sequences) and segment E206 to V217 of the linker module. The acyltransferase module is in yellow, with S*307 of the SxxK motif in red. The linker module is in black with motif 1 (R71 to G79) in green, motif 2 (R167 to G172) in dark blue, motif 3 (G188 to D197) in orange, and segment E206 to V217 in light blue. Motifs 1, 2, and 3 and other peptide segments form the core of the linker module in interaction with a noncatalytic groove of the acyltransferase module. The peptide segment M1 to R71 is of unknown structure. Adapted from reference 148. Illustration courtesy of Robert Brasseur, Faculté Universitaire des Sciences Agronomiques, Gembloux.