Table 2.
Key interactions in the complex structures with β-lactams
| Type of distance | Complex | Distance (Å) |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| CTX-M-9 S70G |
CTX-M-9 S70G/ benzylpenicillin |
CTX-M-9 S70G/piperacillin |
CTX-M-9 S70G/ hydrolyzed benzylpenicillin |
CTX-M-9 S70G/ hydrolyzed piperacillin |
|||||||
| Chain A | Chain B | Chain A | Chain B | Chain A | Chain B | Chain A | Chain B | Chain A | Chain B | ||
| Distance between key residues of the binding sitea | H2O cat-Glu166 (Oε1) | 2.57 | 2.50 | 2.62 | 2.67 | 2.54 | 2.50 | 2.62 | 2.65 | 2.50 | 2.47 |
| H2O cat-Asn170 (Oδ1) | 2.69 | 2.74 | 2.83 | 2.94 | 2.80 | 2.89 | 2.80 | 2.78 | 2.79 | 2.89 | |
| Lys73 (Nζ)-Asn132 (Oδ1) | 2.70 | 2.69 | 2.68 | 2.73 | 2.69 | 2.67–2.76 | 2.65–2.75 | 2.68 | 2.68 | 2.68–2.78 | |
| Lys73(Nζ)-Ser130 (Oγ) | 2.89 | 2.84 | 2.90 | 2.88 | 2.86 | 2.93 | 2.92–3.05 | 2.84 | 2.88 | 2.92 | |
| Ser130 (Oγ)-Lys234 (Nζ) | 2.84 | 2.82 | 2.86 | 2.88 | 2.77 | 2.82 | 2.83 | 2.82 | 2.81 | 2.86 | |
| Glu166 (Oε2)-Asn170 (Nδ2) | 2.74 | 2.76 | 2.74 | 2.78 | 2.79 | 2.81 | 2.73 | 2.81 | 2.81 | 2.83 | |
| Pro167 (O)-Asn170 (N) | 3.07 | 3.17 | 3.04 | 3.09 | 3.16 | 3.26 | 3.12 | 3.20 | 3.20 | 3.27 | |
| Pro167 (O)-Asn170 (Nδ2) | 3.23 | 3.07 | 3.02 | 2.94 | 3.03 | 3.00 | 3.00 | 2.99 | 3.09 | 3.03 | |
| Asn170 (O)-Asp240 (N) | 3.05 | 3.05 | 3.15 | 3.11 | 3.22 | 3.29 | 3.15 | 3.14 | 3.20 | 3.28 | |
| Distance between key residues and amide function of β-lactams | N-12 (β-lactam)–Ser237 (O) | NAb | NA | 2.85 | 2.89 | 2.95 | 2.97 | 2.84 | 2.83 | 2.95 | 3.00 |
| O-14 (β-lactam)–Asn104 (Nδ2) | NA | NA | 3.02 | 3.10 | 3.03 | 2.99 | 3.08 | 3.12 | 3.07 | 3.00 | |
| O-14 (β-lactam)–Asn132 (Nδ2) | NA | NA | 2.90 | 2.93 | 2.91 | 2.90 | 3.01 | 3.01 | 2.90 | 2.91 | |
| Distance between key residues and conserved C-3 carboxylate function of β-lactams | O-11 (β-lactam)–Ser130 (Oγ) | NA | NA | 2.48c | 2.52 | 3.03 | 2.88 | 4.35 | 4.22 | 5.45 | 5.55 |
| O-11 (β-lactam)–Thr235 (Oδ) | NA | NA | 2.56 | 2.62 | 2.70 | 2.92 | 2.61 | 2.65 | 4.82 | 5.01 | |
| O-11 (β-lactam)–Lys234 (Nζ) | NA | NA | 3.03 | 3.07 | 3.65 | 3.74 | 4.53 | 4.44 | 6.74 | 6.89 | |
| O-10 (β-lactam)–Ser237 (Oγ) | NA | NA | 4.36 | 4.00 | 2.79 | 2.62 | 4.51 | 4.51 | 3.03 | 3.03 | |
| Distance between key residues and carbonyl function of the β-lactam ring or the carboxylate resulting from hydrolysis | O-8 (β-lactam)–Gly70 (N) | NA | NA | 2.83 | 2.83 | 2.82 | 2.88 | 2.77 | 2.76 | 2.83 | 2.84 |
| O-8 (β-lactam)–Ser237 (N) | NA | NA | 2.83 | 2.85 | 2.88 | 2.95 | 2.82 | 2.76 | 2.86 | 2.86 | |
| O-8′ (β-lactam)–Lys73 (Nζ) | NA | NA | NA | NA | NA | NA | 2.66 | 2.83 | 2.66 | 2.46 | |
| O-8′ (β-lactam)–Ser130 (Oγ) | NA | NA | NA | NA | NA | NA | 2.49 | 2.43 | 3.00 | 2.98 | |
a
Two distances in monomers A and B. In cases with two distances shown within one monomer, multiple conformations are present.
b
NA, not applicable.
c
Boldface indicates a significant difference in enzyme-ligand distances between complexes.