research papers
The resistance of bacteria to β-lactam antibiotics is primarily caused by the production of β-lactamases. Here, novel crystal structures of the native β-lactamase TEM-171 and two complexes with the widely used inhibitor tazobactam are presented, alongside complementary data from UV spectroscopy and fluorescence quenching. The six chemically identical β-lactamase molecules in the crystallographic asymmetric unit displayed different degrees of disorder. The tazobactam intermediate was covalently bound to the catalytic Ser70 in the trans-enamine configuration. While the conformation of tazobactam in the first complex resembled that in published β-lactamase–tazobactam structures, in the second complex, which was obtained after longer soaking of the native crystals in the inhibitor solution, a new and previously unreported tazobactam conformation was observed. It is proposed that the two complexes correspond to different stages along the deacylation path of the acyl-enzyme intermediate. The results provide a novel structural basis for the rational design of new β-lactamase inhibitors.
Keywords: β-lactamase TEM-171; tazobactam intermediate; antibiotic resistance; enzyme inhibition; crystal structure; UV spectroscopy.
Supporting information
Portable Document Format (PDF) file https://doi.org/10.1107/S2059798322004879/nz5007sup1.pdf |
PDB references: native TEM-171, 2.0 Å resolution, 7qor; complex with tazobactam, 2.3 Å resolution, 7qlp; complex with tazobactam, 2.5 Å resolution, 7qnk