6U58

Toho1 Beta Lactamase Glu166Gln Mutant

Summary for 6U58

• Entry DOI: 10.2210/pdb6u58/pdb
• Descriptor: Beta-lactamase, SULFATE ION (3 entities in total)
• Functional Keywords: hydrolase
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 28295.85

Authors

Langan, P.S.,Sullivan, B.,Weiss, K.L. (deposition date: 2019-08-27, release date: 2020-02-19, Last modification date: 2024-04-03)

Primary citation

Langan, P.S.,Sullivan, B.,Weiss, K.L.,Coates, L.
Probing the Role of the Conserved Residue Glu166 in a Class A Beta-Lactamase Using Neutron and X-ray Protein Crystallography
Acta Crystallogr.,Sect.D, 76:118-123, 2020

PubMed Abstract: The amino-acid sequence of the Toho-1 β-lactamase contains several conserved residues in the active site, including Ser70, Lys73, Ser130 and Glu166, some of which coordinate a catalytic water molecule. This catalytic water molecule is essential in the acylation and deacylation parts of the reaction mechanism through which Toho-1 inactivates specific antibiotics and provides resistance to its expressing bacterial strains. To investigate the function of Glu166 in the acylation part of the catalytic mechanism, neutron and X-ray crystallographic studies were performed on a Glu166Gln mutant. The structure of this class A β-lactamase mutant provides several insights into its previously reported reduced drug-binding kinetic rates. A joint refinement of both X-ray and neutron diffraction data was used to study the effects of the Glu166Gln mutation on the active site of Toho-1. This structure reveals that while the Glu166Gln mutation has a somewhat limited impact on the positions of the conserved amino acids within the active site, it displaces the catalytic water molecule from the active site. These subtle changes offer a structural explanation for the previously observed decreases in the binding of non-β-lactam inhibitors such as the recently developed diazobicyclooctane inhibitor avibactam.

PubMed: 32038042
DOI: 10.1107/S2059798319016334

Experimental method

NEUTRON DIFFRACTION (1.89 Å)
X-RAY DIFFRACTION (1.9 Å)