PDBsum entry 1esu

Hydrolase

PDB id: 1esu

Contents

Protein chain

263 a.a. *

Ligands

SO4

Waters ×137

* Residue conservation analysis

PDB id:

1esu

Name:

Hydrolase

Title:

S235a mutant of tem1 beta-lactamase

Structure:

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

Source:

Escherichia coli. Organism_taxid: 562. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.00Å R-factor: 0.162

Authors:

E.Fonze,P.Charlier

Key ref:

E.Fonzé et al. (1995). TEM1 beta-lactamase structure solved by molecular replacement and refined structure of the S235A mutant. Acta Crystallogr D Biol Crystallogr, 51, 682-694. PubMed id: 15299797 DOI: 10.1107/S0907444994014496

Date:

11-Apr-00 Release date: 03-May-00

Protein chain

P62593  (BLAT_ECOLX) -  Beta-lactamase TEM from Escherichia coli

Seq: 286 a.a.

Struc: 263 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: Zn(2+)

DOI no: 10.1107/S0907444994014496

Acta Crystallogr D Biol Crystallogr 51:682-694 (1995)

PubMed id: 15299797

TEM1 beta-lactamase structure solved by molecular replacement and refined structure of the S235A mutant.

E.Fonzé, P.Charlier, Y.To'th, M.Vermeire, X.Raquet, A.Dubus, J.M.Frère.

ABSTRACT

beta-Lactamases are bacterial enzymes which catalyse the hydrolysis of the beta-lactam ring of penicillins, cephalosporins and related compounds, thus inactivating these antibiotics. The crystal structure of the TEM1 beta-lactamase has been determined at 1.9 A resolution by the molecular-replacement method, using the atomic coordinates of two homologous beta-lactamase refined structures which show about 36% strict identity in their amino-acid sequences and 1.96 A r.m.s. deviation between equivalent Calpha atoms. The TEM1 enzyme crystallizes in space group P2(1)2(1)2(1) and there is one molecule per asymmetric unit. The structure was refined by simulated annealing to an R-factor of 15.6% for 15 086 reflections with I >/= 2sigma(I) in the resolution range 5.0-1.9 A. The final crystallographic structure contains 263 amino-acid residues, one sulfate anion in the catalytic cleft and 135 water molecules per asymmetric unit. The folding is very similar to that of the other known class A beta-lactamases. It consists of two domains, the first is formed by a five-stranded beta-sheet covered by three alpha-helices on one face and one alpha-helix on the other, the second domain contains mainly alpha-helices. The catalytic cleft is located at the interface between the two domains. We also report the crystallographic study of the TEM S235A mutant. This mutation of an active-site residue specifically decreases the acylation rate of cephalosporins. This TEM S235A mutant crystallizes under the same conditions as the wild-type protein and its structure was refined at 2.0 A resolution with an R value of 17.6%. The major modification is the appearance of a water molecule near the mutated residue, which is incompatible with the OG 235 present in the wild-type enzyme, and causes very small perturbations in the interaction network in the active site.

Selected figure(s)

Figure 10.
Fig. 10. Structural comparison of the orientation of the 244 side chain in TEM1 and R220 in SaG (in grey) relative to the active serine $70 of TEM1. The Ca trace is represented as a ribbon.

Figure 12.
Fig. 12. Superposition of the active sites of EM1 (magenta) and of its $235A

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (1995, 51, 682-694) copyright 1995.

Figures were selected by an automated process.