Fig. 3

Schematic presentation of S. aureus PBP3 and PBP3 fragments expressed as His-tagged recombinant proteins. The PBP3 of S. aureus (SA-PBP3) with a non-penicillin binding (n-PB) dimerization domain connected by an inter-domain hinge to a penicillin binding (PB) transpeptidase domain is shown uppermost. ΔPBP3 is encoded by the FTP library clone and it carries an N-terminal signal for secretion (FliC) and a C-terminal FLAG-tag encoded by the expression vector pSRP18/0. The recombinant protein named PBP3-C_S634 carries eight N-terminal histidine residues and the truncated sequence of the penicillin binding (PB) domain of PBP3. The recombinant protein named PBP3-C carries eight N-terminal histidine residues and the sequence of the penicillin binding (PB) domain of PBP3. The recombinant protein PBP3-F carries an N-terminal hexahistidine tag (His), the non-penicillin (n-PB) and penicillin binding (PB) domains, but lacks the N-terminal membrane anchor sequence (Anchor) of native PBP3. The N- and C-terminal amino acid residues of the domains are indicated below each protein. The lysine-rich sequences of SA-PBP3 are indicated (KDEVGPLKKKINGTVLNKVNNTEKEIK and KGLGKDDKNKDKDK)