PDBsum entry 1qjf

B-lactam antibiotic

PDB id: 1qjf

Contents

Protein chain

328 a.a. *

Ligands

SO4

ACS

Metals

FE2

Waters ×410

* Residue conservation analysis

PDB id:

1qjf

Name:

B-lactam antibiotic

Title:

Isopenicillin n synthase from aspergillus nidulans (monocyclic sulfoxide - fe complex)

Structure:

Isopenicillin n synthase. Chain: a. Engineered: yes

Source:

Emericella nidulans (strain fgsc a4 / atcc 38163 / cbs 112.46 / nrrl 194 / m139). Aspergillus nidulans. Organism_taxid: 227321. Gene: pcb c. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.40Å R-factor: 0.131 R-free: 0.205

Authors:

P.J.Rutledge,I.J.Clifton,N.I.Burzlaff,P.L.Roach,R.M.Adlington, J.E.Baldwin

Key ref:

N.I.Burzlaff et al. (1999). The reaction cycle of isopenicillin N synthase observed by X-ray diffraction. Nature, 401, 721-724. PubMed id: 10537113 DOI: 10.1038/44400

Date:

23-Jun-99 Release date: 29-Jun-00

Protein chain

P05326  (IPNS_EMENI) -  Isopenicillin N synthase from Emericella nidulans (strain FGSC A4 / ATCC 38163 / CBS 112.46 / NRRL 194 / M139)

Seq: 331 a.a.

Struc: 328 a.a.

Enzyme reactions

• Enzyme class: E.C.1.21.3.1 - isopenicillin-N synthase.
• Pathway: Penicillin N and Deacetoxycephalosporin C Biosynthesis
• Reaction: N-[(5S)-5-amino-5-carboxypentanoyl]-L-cysteinyl-D-valine + O2 = isopenicillin N + 2 H2O

N-[(5S)-5-amino-5-carboxypentanoyl]-L-cysteinyl-D-valine + O2 = isopenicillin N + 2 × H2O (Bound ligand (Het Group name = ACS) matches with 81.48% similarity)

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

Added reference

DOI no: 10.1038/44400

Nature 401:721-724 (1999)

PubMed id: 10537113

The reaction cycle of isopenicillin N synthase observed by X-ray diffraction.

N.I.Burzlaff, P.J.Rutledge, I.J.Clifton, C.M.Hensgens, M.Pickford, R.M.Adlington, P.L.Roach, J.E.Baldwin.

ABSTRACT

Isopenicillin N synthase (IPNS), a non-haem iron-dependent oxidase, catalyses the biosynthesis of isopenicillin N (IPN), the precursor of all penicillins and cephalosporins. The key steps in this reaction are the two iron-dioxygen-mediated ring closures of the tripeptide delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine (ACV). It has been proposed that the four-membered beta-lactam ring forms initially, associated with a highly oxidized iron(iv)-oxo (ferryl) moiety, which subsequently mediates closure of the five-membered thiazolidine ring. Here we describe observation of the IPNS reaction in crystals by X-ray crystallography. IPNS Fe2+ substrate crystals were grown anaerobically, exposed to high pressures of oxygen to promote reaction and frozen, and their structures were elucidated by X-ray diffraction. Using the natural substrate ACV, this resulted in the IPNS x Fe2+ x IPN product complex. With the substrate analogue, delta-(L-alpha-aminoadipoyl)-L-cysteinyl-L-S-methylcysteine (ACmC) in the crystal, the reaction cycle was interrupted at the monocyclic stage. These mono- and bicyclic structures support our hypothesis of a two-stage reaction sequence leading to penicillin. Furthermore, the formation of a monocyclic sulphoxide product from ACmC is most simply explained by the interception of a high-valency iron-oxo species.

Selected figure(s)

Figure 2.
Figure 2 Proposed mechanisms for the oxidation of ACV and ACmC to bicyclic and monocyclic products, respectively. See text for details of compounds 1-6. AA, L- -( -aminoadipoyl).

Figure 3.
Figure 3 Stereo views of the two substrates and two products overlaid. The key regions that participate in the reaction and the iron atom (orange) are shown; the aminoadipoyl side chain, which does not move significantly, is omitted for clarity. Shown are ACV (white), IPN (yellow), ACmC (blue) and its monocyclic sulphoxide product (pink). Figures were prepared using the programs MOLSCRIPT20 and Raster3D (ref. 21).

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (1999, 401, 721-724) copyright 1999.

Figures were selected by an automated process.