PDBsum entry: 1bza

Hydrolase

PDB id: 1bza

Contents

Protein chain

257 a.a. *

Ligands

SO4 ×2

Waters ×405

* Residue conservation analysis

PDB id:

1bza

Name:

Hydrolase

Title:

Beta-lactamase toho-1 from escherichia coli tuh12191

Structure:

Beta-lactamase. Chain: a. Engineered: yes. Mutation: yes

Source:

Escherichia coli. Organism_taxid: 562. Strain: tuh12191. Cellular_location: periplasm. Gene: bla. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.80Å R-factor: 0.182 R-free: 0.217

Authors:

A.Ibuka,A.Taguchi,M.Ishiguro,S.Fushinobu,Y.Ishii,S.Kamitori, K.Okuyama,K.Yamaguchi,M.Konno,H.Matsuzawa

Key ref:

A.Ibuka et al. (1999). Crystal structure of the E166A mutant of extended-spectrum beta-lactamase Toho-1 at 1.8 A resolution. J Mol Biol, 285, 2079-2087. PubMed id: 9925786 DOI: 10.1006/jmbi.1998.2432

Date:

28-Oct-98 Release date: 27-Apr-99

Protein chain

Q47066  (BLT1_ECOLX) -  Beta-lactamase Toho-1

Seq: 291 a.a.

Struc: 257 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.3.5.2.6 - Beta-lactamase.
• Pathway: Penicillin Biosynthesis and Metabolism
• Reaction: A beta-lactam + H₂O = a substituted beta-amino acid
• Cofactor: Zinc

 Gene Ontology (GO) functional annotation 

• Biological process: response to antibiotic (2 terms)
• Biochemical function: hydrolase activity (2 terms)

DOI no: 10.1006/jmbi.1998.2432

J Mol Biol 285:2079-2087 (1999)

PubMed id: 9925786

Crystal structure of the E166A mutant of extended-spectrum beta-lactamase Toho-1 at 1.8 A resolution.

A.Ibuka, A.Taguchi, M.Ishiguro, S.Fushinobu, Y.Ishii, S.Kamitori, K.Okuyama, K.Yamaguchi, M.Konno, H.Matsuzawa.

ABSTRACT

Bacterial resistance to beta-lactams is mainly due to the production of beta-lactamase. Especially through the production of extended-spectrum beta-lactamases (ESBLs), bacteria have acquired resistance not only to penicillins, but also to expanded-spectrum cephems. Here, we describe the crystal structure of the E166A mutant of class A beta-lactamase Toho-1 at 1.8 A resolution, the first reported tertiary structure of an ESBL. Instead of the wild-type enzyme, a mutant Toho-1, in which Glu166 was replaced with alanine, was used for this study, because of the strong tendency of the wild-type enzyme to form twinned crystals. The overall structure of Toho-1 is similar to the crystal structures of non-ESBLs, with no pronounced backbone rearrangement of the framework. However, there are some notable local changes. First, a difference in the disposition of an arginine residue, which is at position 244 in non-ESBLs but at position 276 in Toho-1 and other ESBLs, was revealed and the role of this arginine residue is discussed. Moreover, changes in the hydrogen-bonding pattern and in the formation of the hydrophobic core were also observed near the Omega loop. In particular, the lack of hydrogen bonds in the vicinity of the Omega loop could be a cause of the extended substrate specificity of Toho-1. Through the generation of a model for the enzyme-substrate complex, a conformational change of Toho-1 occurring on complex formation is discussed based on the active-site cleft structure and the substrate profile.

Selected figure(s)

Figure 2.
Figure 2. A stereo view of the hydrogen-bonding net- work in the active-site cleft of Toho-1. Water oxygen atoms are shown as red balls, and the hydrogen bonds as broken lines. The sulfate ion is shown by sticks at the center of the cleft. This Figure was generated with MOLMOL (Koradi et al., 1996).

Figure 5.
Figure 5. Hydrogen-bonding pat- tern near Asp240. The main-chain and hydrogen bonds of Toho-1 are shown in blue and green, respect- ively, and those of B. licheniformis b-lactamase in pink and magenta. The water molecule of Toho-1 is colored red, and that of B. licheni- formis b-lactamase pink.

The above figures are reprinted by permission from Elsevier: J Mol Biol (1999, 285, 2079-2087) copyright 1999.

Figures were selected by an automated process.