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. 2012 Dec 21;7(12):e52283. doi: 10.1371/journal.pone.0052283

Figure 1. Sequence blocks exchanged between parental TEM-1 and PSE-4 β-lactamases in the selected, functional chimeras.

Figure 1

A) Numbering of the sequence blocks originating from TEM-1 (blue) and PSE-4 (red) in cTEM-17m, cTEM-67m and cTEM-92m, according to the Ambler numbering [64]. The nomenclature of the chimeras is as follows: ‘c’ indicates chimeragenesis, and the number refers to the number of substitutions (or mutations: ‘m’) in each chimera relative to the TEM-1 parental sequence. The catalytic nucleophile, Ser70, and the catalytically-relevant Ω-loop, are indicated to highlight their parental origin. B) Structural representation of the sequence blocks exchanged during chimeragenesis, coloured according to parental origin as in panel A. The TEM-1 coordinates (PDB 1ZG4) were used for the representation. C) The sequence identity to each parental sequence is given. TEM-1 and PSE-4 differ by 150 residues (for a sequence identity of 40%) between residues 26 (the N-terminus following cleavage of the leader sequence of TEM-1) to 290 (C-terminus of TEM-1). The deletion at position 58 in PSE-4 is considered as a mutation relative to TEM-1. Thus, the additional four residues at the N-terminus and five residues at the C-terminus of PSE-4 are not included in the comparison to TEM-1.