Crystal structures of penicillin‐binding protein 3 in complexes with azlocillin and cefoperazone in both acylated and deacylated forms

Abstract

Penicillin‐binding protein 3 (PBP3) from Pseudomonas aeruginosa is the molecular target of β‐lactam‐based antibiotics. Structures of PBP3 in complexes with azlocillin and cefoperazone, which are in clinical use for the treatment of pseudomonad infections, have been determined to 2.0 Å resolution. Together with data from other complexes, these structures identify a common set of residues involved in the binding of β‐lactams to PBP3. Comparison of wild‐type and an active site mutant (S294A) showed that increased thermal stability of PBP3 following azlocillin binding was entirely due to covalent binding to S294, whereas cefoperazone binding produces some increase in stability without the covalent link. Consistent with this, a third crystal structure was determined in which the hydrolysis product of cefoperazone was noncovalently bound in the active site of PBP3. This is the first structure of a complex between a penicillin‐binding protein and cephalosporic acid and may be important in the design of new noncovalent PBP3 inhibitors.

Recognition of the β-lactam carboxylate triggers acylation of Neisseria gonorrhoeae penicillin-binding protein 2

“…S10). Similar flexibility of this region has also been observed in other PBP structures (26,27,34,38). In P. aeruginosa PBP3 (a homolog of N. gonorrhoeae PBP2), the equivalent residues (Tyr-532 and Phe-533) along with Phe-503, have been characterized as an aromatic "wall" that accommodates the gem-dimethyl group of ceftazidime (26).…”

“…Consistent with this, elimination of the C3 substituents of ceftazidime and cefoperazone also elicits a rearrangement to the exocyclic form in crystal structures of Pseudomonas aeruginosa PBP3 (26,27).…”

Azlocillin can be the potential drug candidate against drug-tolerant Borrelia burgdorferi sensu stricto JLB31

“…The β-lactam drugs bind to PBPs and prevent either transglycosylation or transglycosylation steps which leads to disruption of bacterial of cell wall synthesis 51 . The crystallography structural studies shows azlocillin binds strongly to penicillin-binding protein 3 (PBP 3) of Pseudomonas aeruginosa 34 . Considering these studies, we have performed in silico analysis of azlocillin interacting with pencillin-binding protein of Borrelia burgdorferi (PBP-3Bb).…”

“…Since the 3D structure for the pencillin-binding protein of Borrelia burgdorferi (PBP-3Bb) has not been resolved, its 3D structure was predicted using homology modeling. Penicillin-binding protein 1 A (PBP-1A) of Pseudomonas aeruginosa (PDB ID: 5DF7), for which 3D structure is available (PDB ID: 4OON), was found to have 39% sequence similarity with PBP-3Bb 34 . Therefore, 4OON was used as the template to build the 3D structure of PBP-3Bb; in the modeled structure of PBP-3Bb, 87.1% of the amino acids were observed to be in the most favored region while 11.4% were in addition allowed region of the Ramachandran plot (supplementary Figure 1).…”

Synthesis and biochemical evaluation of cephalosporin analogues equipped with chemical tethers

“…Previously reported thermal shi assays with PBPs have noted both increases and decreases in T m of the protein aer the binding of different b-lactam analogues. [15][16][17] Further thermal shi studies were carried out to approximate the affinities of compounds 1-12 with PBP3. PBP3 was selected for this study as this particular PBP is essential for cell division in E. coli, making PBP3 an important target for b-lactam antibiotics.…”