PDBsum entry 1keh

Hydrolase

PDB id: 1keh

Contents

Protein chain

683 a.a. *

Waters ×399

* Residue conservation analysis

PDB id:

1keh

Name:

Hydrolase

Title:

Precursor structure of cephalosporin acylase

Structure:

Precursor of cephalosporin acylase. Chain: a. Fragment: residues 1-689. Synonym: glutaryl 7-aminocephalosporanic acid acylase precursor. Engineered: yes. Mutation: yes

Source:

Brevundimonas diminuta. Organism_taxid: 293. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.50Å R-factor: 0.203 R-free: 0.237

Authors:

Y.Kim,S.Kim

Key ref:

Y.Kim et al. (2002). Precursor structure of cephalosporin acylase. Insights into autoproteolytic activation in a new N-terminal hydrolase family. J Biol Chem, 277, 2823-2829. PubMed id: 11706000 DOI: 10.1074/jbc.M108888200

Date:

16-Nov-01 Release date: 16-May-02

Protein chain

Q9L5D6  (G7AC_BREDI) -  Glutaryl-7-aminocephalosporanic-acid acylase from Brevundimonas diminuta

Seq: 720 a.a.

Struc: 683 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.5.1.93 - glutaryl-7-aminocephalosporanic-acid acylase.
• Reaction: (7R)-7-(4-carboxybutanamido)cephalosporanate + H2O = (7R)-7- aminocephalosporanate + glutarate

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1074/jbc.M108888200

J Biol Chem 277:2823-2829 (2002)

PubMed id: 11706000

Precursor structure of cephalosporin acylase. Insights into autoproteolytic activation in a new N-terminal hydrolase family.

Y.Kim, S.Kim, T.N.Earnest, W.G.Hol.

ABSTRACT

Autocatalytic proteolytic cleavage is a frequently observed post-translational modification in proteins. Cephalosporin acylase (CA) is a recently identified member of the N-terminal hydrolase family that is activated from an inactive precursor by autoproteolytic processing, generating a new N-terminal residue, which is either a Ser or a Thr. The N-terminal Ser or Thr becomes a nucleophilic catalytic center for intramolecular and intermolecular amide cleavages. The gene structure of the open reading frame of CAs generally consists of a signal peptide followed by the alpha-subunit, a spacer sequence, and the beta-subunit, which are all translated into a single polypeptide chain, the CA precursor. The precursor is post-translationally modified into an active heterodimeric enzyme with alpha- and beta-subunits, first by intramolecular cleavage and second by intermolecular cleavage. We solved the first CA precursor structure (code 1KEH) from a class I CA from Pseudomonas diminuta at a 2.5-A resolution that provides insight into the mechanism of intramolecular cleavage. A conserved water molecule, stabilized by four hydrogen bonds in unusual pseudotetrahedral geometry, plays a key role to assist the OG atom of Ser(1beta) to generate a strong nucleophile. In addition, the site of the secondary intermolecular cleavage of CA is proposed to be the carbonyl carbon of Gly(158alpha) (Kim, S., and Kim, Y., (2001) J. Biol. Chem., 276, 48376-48381), which is different from the situation in two other class I CAs.

Selected figure(s)

Figure 2.
Fig. 2. A, stereo view of the S1 A precursor CAD. The precursor structure is a single chain protein, consisting of the subunit of active CAD in green, a red P-loop (spacer structure in loop form), and the -subunit of CAD in yellow. The view is looking at the side from the active site cleft. The side-chain pocket for binding the substrate GL-7-ACA is represented by a ball-and-stick model in the center (16). The first six residues of S1 A precursor CAD are disordered, and thus the label N in the -subunit indicates the locations of Gln7 . B, an orthogonal view of panel A.

Figure 3.
Fig. 3. Superposition of CAD and S1 A precursor CAD structures. Nine interacting residues with the substrate (16), GL-7-ACA, are superimposed onto each other. Active site residues are shown in ball-and-stick models. The S1 A precursor CAD is shown in gray, and the CAD structure is shown in black. The mutation of Ser1 to Ala is labeled as S1 A in the precursor CAD.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 2823-2829) copyright 2002.

Figures were selected by an automated process.